It has been known for a long time KD was listed at 6’9 which may have been his height entering the league, but after a few years he grew (very evidently) and was closer to 7ft. After 10+ years the NBA listed him at 6’10 and this year, finally he is listed at 6’11 officially.
I’ve stood next to him while he was standing next to Myles Turner. Myles was at least 2 inches taller than Durant, and is also listed at 6’11”. I don’t think Durant is any taller than 6’10”.