Degrees of real:
-- Is it a physical item? Yes.
-- Is it the right design and colors? Appears to be.
-- Was it made for the team's players to wear (as opposed to just some fan jersey on sale somewhere)? Can't help you there.
-- Did a player actually wear it? Ditto.
-- Did a player actually wear it in a game? If you don't see any grass, sweat, or blood stains, this is unlikely.
Good luck, I hope it's as real as you want it to be!
p.s. At some point in the very early days of the idea of NIL, schools stopped selling jerseys with any player number they didn't already have rights to. Like, I think at that point, Tennessee stopped endorsing or selling any jersey other than those we've retired, like Peyton's #16. That info might help in some way. Cheers!