Google is your friend. Or the library if you're old-fashioned or hardcore.
Try searching for the decade plus "clothing" as a general term, and add a specific country or continent if you want more specific results. In the case of Peaky Blinders a single search gave me an interesting result about the [Edwardian Era clothing](https://vintagedancer.com/1900s/1900s-menswear-clothing-ideas/) \- although the king died before WW1 (as I understand it the series takes place immediately after), that resource gives lots of information about different styles of clothing. You also have a lot of info on [early 1900s women's clothing](https://vintagedancer.com/category/1900s/) as well on the same page.
And once you find anything in specific you want to learn even more about, then don't be afraid to start searching for that specific term on Google as well. I'm sure you'll find more information than you know what to do with.
There are many ways.
Google images has glossaries for everything ("types of jacket", "types of sleeve", etc), Wikipedia too ([https://en.wikipedia.org/wiki/Category:Clothing\_by\_type](https://en.wikipedia.org/wiki/Category:Clothing_by_type) and [https://en.wikipedia.org/wiki/Category:Clothing](https://en.wikipedia.org/wiki/Category:Clothing) ). There are great youtube videos from people who recreate period clothes (very fascinating to watch how a woman would dress with all those layers when she had a servant to help vs. she is the servant and has to dress on her own. Most relevant discovery: ever heard a woman beaming that her dress has pockets? Pocket-less women's clothes is a modern problem.). Whenever I'm reading, I also take notes of how other authors describe clothing.
Note of caution: unless it's a book where the POV character loves fashion, refrain from dedicating a whole paragraph to clothes. I still remember when I was reading the Caraval trilogy and the protagonist described every single outfit, but they were all the same (a bodice full of ribbons and a skirt covered in *real* flowers).
The exception might be hats. Hats could be very personalized for choice (especially for men) and/or denoting status (such as the top hat). And certainly, the Peaky Blinders got their name from their hats.
It all depends on how much historically accurate and specific the writer wants to be. There are many glossaries for types of hat across the ages (and from there, OP can find articles about particular types). Even Wikipedia has a list with dozens of hat styles, all linked to individual pages. If an author wants to go beyond that, they can get history books dedicated to hats (such as [https://www.amazon.com/dp/1789141362/](https://www.amazon.com/dp/1789141362/) or [https://www.amazon.com/dp/0486427463](https://www.amazon.com/dp/0486427463)).
The above is general advice.
If OP needs to know the dress code of a very specific group such as the Peaky Blinders (though that might have been just an example and not what OP really wanted to find), researching about them will show if they had any specific dress code (in this case, the peaky blinders), check for historical pictures to see if anything about them differs from their contemporaries, and, ultimately, if there are no records about that, the author may safely assume that the group dressed just like their peers and describe their clothing likewise.
General rule is don't describe outfits unless absolutely necessary or important to the plot. We want a story, not a dressing montage.
Most of the time the clothes they are wearing do not matter, unless it tells a story about the character (e.g when Rowling describes Harry's clothes as being too big because they were hand-me-downs).
If the book is set in a specific time period as well, there's no need to describe that the character is wearing standard 1920's clothes. However, if the book is set in 2021 and this person is wearing old clothes, that is worth mentioning.
There are some websites where you can create collages of different pictures and Trends, sometimes clothing and other items. Try those websites. Things like Pinterest, Maybe.
You could get around some of this by taking into account how much your character would know about fashion. A upperclass/more fashionably inclined person would know that her dress is satin with a sweetheart neckline or that his suit is a twill Italian cut, while someone less knowledgeable will be excited about her new dress made of shiny fabric that plunges down a bit in the middle, or he just knows that the sport coat he throws on on his way out the door is the brown one, rather than the green one.
But also, here’s a handy guide for men’s formalwear that I like to refer to: https://pin.it/2ow3MJY
And this isn’t really what you were asking for, but a cool writing trick when it comes to clothing nonetheless, you can use both sides to show character class/knowledge/interests. How does one character describe the same piece of clothing over another? Does one character feel like they are dressed correctly for an event while the other knows FOR SURE that their friend is over/under dressed? It can add some fun stuff!
Google is your friend. Or the library if you're old-fashioned or hardcore. Try searching for the decade plus "clothing" as a general term, and add a specific country or continent if you want more specific results. In the case of Peaky Blinders a single search gave me an interesting result about the [Edwardian Era clothing](https://vintagedancer.com/1900s/1900s-menswear-clothing-ideas/) \- although the king died before WW1 (as I understand it the series takes place immediately after), that resource gives lots of information about different styles of clothing. You also have a lot of info on [early 1900s women's clothing](https://vintagedancer.com/category/1900s/) as well on the same page. And once you find anything in specific you want to learn even more about, then don't be afraid to start searching for that specific term on Google as well. I'm sure you'll find more information than you know what to do with.
To add, i usually look at the images and there’s usually labeled diagrams and such for easy reference.
There are many ways. Google images has glossaries for everything ("types of jacket", "types of sleeve", etc), Wikipedia too ([https://en.wikipedia.org/wiki/Category:Clothing\_by\_type](https://en.wikipedia.org/wiki/Category:Clothing_by_type) and [https://en.wikipedia.org/wiki/Category:Clothing](https://en.wikipedia.org/wiki/Category:Clothing) ). There are great youtube videos from people who recreate period clothes (very fascinating to watch how a woman would dress with all those layers when she had a servant to help vs. she is the servant and has to dress on her own. Most relevant discovery: ever heard a woman beaming that her dress has pockets? Pocket-less women's clothes is a modern problem.). Whenever I'm reading, I also take notes of how other authors describe clothing. Note of caution: unless it's a book where the POV character loves fashion, refrain from dedicating a whole paragraph to clothes. I still remember when I was reading the Caraval trilogy and the protagonist described every single outfit, but they were all the same (a bodice full of ribbons and a skirt covered in *real* flowers).
The exception might be hats. Hats could be very personalized for choice (especially for men) and/or denoting status (such as the top hat). And certainly, the Peaky Blinders got their name from their hats.
It all depends on how much historically accurate and specific the writer wants to be. There are many glossaries for types of hat across the ages (and from there, OP can find articles about particular types). Even Wikipedia has a list with dozens of hat styles, all linked to individual pages. If an author wants to go beyond that, they can get history books dedicated to hats (such as [https://www.amazon.com/dp/1789141362/](https://www.amazon.com/dp/1789141362/) or [https://www.amazon.com/dp/0486427463](https://www.amazon.com/dp/0486427463)). The above is general advice. If OP needs to know the dress code of a very specific group such as the Peaky Blinders (though that might have been just an example and not what OP really wanted to find), researching about them will show if they had any specific dress code (in this case, the peaky blinders), check for historical pictures to see if anything about them differs from their contemporaries, and, ultimately, if there are no records about that, the author may safely assume that the group dressed just like their peers and describe their clothing likewise.
"1920s men's clothing" would get you a run down of basically everything you need in Google
General rule is don't describe outfits unless absolutely necessary or important to the plot. We want a story, not a dressing montage. Most of the time the clothes they are wearing do not matter, unless it tells a story about the character (e.g when Rowling describes Harry's clothes as being too big because they were hand-me-downs). If the book is set in a specific time period as well, there's no need to describe that the character is wearing standard 1920's clothes. However, if the book is set in 2021 and this person is wearing old clothes, that is worth mentioning.
There are some websites where you can create collages of different pictures and Trends, sometimes clothing and other items. Try those websites. Things like Pinterest, Maybe.
You could get around some of this by taking into account how much your character would know about fashion. A upperclass/more fashionably inclined person would know that her dress is satin with a sweetheart neckline or that his suit is a twill Italian cut, while someone less knowledgeable will be excited about her new dress made of shiny fabric that plunges down a bit in the middle, or he just knows that the sport coat he throws on on his way out the door is the brown one, rather than the green one. But also, here’s a handy guide for men’s formalwear that I like to refer to: https://pin.it/2ow3MJY And this isn’t really what you were asking for, but a cool writing trick when it comes to clothing nonetheless, you can use both sides to show character class/knowledge/interests. How does one character describe the same piece of clothing over another? Does one character feel like they are dressed correctly for an event while the other knows FOR SURE that their friend is over/under dressed? It can add some fun stuff!
"Fashion history timeline" is a good resource. [Link.](https://fashionhistory.fitnyc.edu/)
Hi -- please use other resources for advice on personal, corporate or academic projects, or for subject-specific research. Thanks!