Not at their ages, you see it a lot in youth football but by the time they get to the 1st team they're usually set, especially the ones that have played 1st team football for years.
Pep just sees the game better than most though.
I think partly it's because he has the authority to do so. It's a bit different with Nico and Zinchenko as they were teenagers when he moved them, but if most managers went to a 26 year old £53m signing and said "You're a right back now" they'd either tell him to fuck off, or just not buy into it so it wouldn't work.
Pep's earned the authority and trust of any footballer so if he decides to move you around, you go for it.