He wear's size 12 shoe and his hands are small he's 5,9 and 21 could he still have a growth spurt in him his also 315 pounds?

Maybe: Often foot size precedes other growth. A good exam to look at his puberty status and a wrist XR to look at his growth plates would be information helpful to him. All the best.

Not often: By 17 most males see their growth centers begin to close and growth slows,by 21 almost all have stopped.An x-ray of the hand can be analysed to see what stage the growth is entering. Some "late bloomers"continue slow steady growth into their early 20's.