>> it IS oversized <<
Depends upon your size, I guess. I'm 6'0", 200 lbs. I don't know about anything else, but I used to be able to buy XL "business-casual" short-sleeved shirts from A&F, and they fit me fine (loose in the shoulders, and long enough to tuck in).
Nowadays the XLs are tighter and shorter. I didn't change, so they must've. I'd buy XXLs if I could find any, but my local A&F doesn't seem to have any, and their website is pretty poor, IMO. Even if you can get past all the images of the half-naked men, they have a very limited selection of items available online, and picking out a shirt based on a tiny scan viewed on a monitor is difficult at best.