Google and you will find many pictures of Embiid standing next to Nerlens Noel, standing almost exactly as tall as Nerlens' hair. It was well-documented that, with his flat top, Nerlens was 7' when drafted. Embiid at the time was buzzed. Now he has a fro.
Basically, what I'm saying is that there is a 2" margin of error here.
But it's the off season, where everyone is in the best shape of his life, everyone under 21 has grown remarkably taller, everyone over 30 has lost weight and gotten faster, and everyone under 30 has put on 15 pounds of muscle.