First Steps" introduced the most powerful being in the MCU -Franklin Richards – and was pretty nonchalant about it.

Franklin’s powers allowed him to create the universe, dimensions, avoid mind control, and every other cool power you can think of. Franklin Richards is considered a Beyond Omega Level mutant, and he is the only one in that category, making him the most powerful mutant on Earth.

In a 1982 arc by John Byrne, Franklin gets frustrated trying to solve a Rubik’s Cube and uses his powers to age himself into an adult body, though he couldn’t actually gain more emotional maturity. He winds up going back to being a kid, placing restrictions on his own abilities to allow him to have something of a normal childhood.