Atlas' shirt would be the same as the one here ^^
I kind of see the shirts being a little big on him, but that's just because Modern!Atlas has sweaterpaw potential (I also feel like he'd wear flannels a lot and have glasses? Don't know why but it seems right).

As for pants, he'd wear those weird capris that don't taper a whole lot so they're still loose around his shins. He doesn't wear shoes very often, so barefoot is best.

strxwberryymilk