There are accounts using fake pics all the time.That uses Theo’s pics?
Just pick some good looking and not-too-famous person's Instagram and download some stuff and create your own account using those pictures. Maybe bad idea to use Henry Cavill or Jostin Bieber but there are plenty of hot dudes who post risqué stuff from the gym.
Heck I've seen Grindr accounts with pictures of Johnny Sins and I found an account on a Swedish gay community who was using the pass-card picture of a friend of mine (who is very much not gay).
People steal pictures all the time and pretend to be someone else.