The multiverse has become a central part of the Marvel Cinematic Universe. Instead of just focusing on Earth-616, numerous movies and shows have ushered in the concept of a multiverse. Loki, Doctor Strange in the Multiverse of Madness, Spider-Man: No Way Home, and What If...? have all revolved around it, and each has had its spin on the idea of heroic and villainous variants.
Source：https://www.cbr.com/mcu-heroes-multiversal-variants/
