Rhode Island Whites are extremely rare. His leg color, tail length, and general plumage color are wrong for a RIW. I'm just gonna call him a pretty mutt.
He has yellow on his shoulders. Also, Wyandottes have yellow legs (his are white) and small, short tails. Even hatchery Wyandottes have long tails, but they're very upright and thin looking.
If you crossed this with another breed(s) that would give him a rose comb, shorten most of his feathers, and change the red on the shoulders to gold... This is my best guess!