Even if he played high school football, he hasn't played the sport in years. He would have to learn a position essentially from scratch. The kinds of contact in each sport are very different, so he'd have to dive into a different S&C program just to be physically ready to play.
Whatever position he would play, there are football scholarship players who have been in the program for years. He would have to pass them on the depth chart; and because the football staff is committed to its own scholarship players first, being the equal of his teammates won't get him significant playing time (if any at all). He would have to be obviously better.
If Perkovic really were interested in football, going to a lower level D1-A or a D1-AA school as a graduate transfer would be the smart move. At that level, he would be a more gifted athlete than almost all of his teammates. He'd still have to adapt in other ways, but his size and athletic ability compared to teammates would make it hard to keep him off the field.