In Marvel Comics, Franklin Richards is an immensely powerful mutant who can alter reality itself. This comes from the cosmic ray-mutated genes he inherited from his parents. "The Fantastic Four: First Steps" depicts Franklin in the same way; his powerful potential is the driving force of the movie.

Doomsday connects to The Fantastic Four: First Steps? A key mid-credits scene introduces a mysterious presence, hints at a growing multiversal threat, and sets up one character’s deeper interest in Franklin Richards.

First Steps' includes two post-credits scenes. Here's how that big reveal sets up what's coming in Phase 6 of the MCU.