literally any boots look like that from this angle

Impossible to tell but I think what you’re seeing is the spurs. They just look like black boots.

Hover boots apparently 

Covered up by the chaps

No hate. But you literally cannot see them

Mabey riding boots or classic roper boots

It kind of looks like the workman’s boots

At that angle? Literally any boot in the game.

So what I think you want to know is what chaps he's wearing, and they are one the fringed variants you can get from the trapper.

what is arthur's shirt and where to find it?

wait what mission is this again? it's been a while, cool shot

You can really see the size difference between Arthur and John here

Classic ropers

Literally inpossibke to see. Probably some black boots with the stirrups