Question: do x-men and avengers exist in the same universe?
Answer: Yet, for now, still, the X-Men mutants and the Avengers do not co-exist in the same universe. It's a comics-based world, though, and maybe the Quantum Realm will change all that we know about the current MCU timeline. The MCU is now comprised of 21 Marvel Studios films and began over 10 years ago with Iron Man.