I'm not all that across the MCU, but if the idea is that the PCs become the world-shattering/saving heroes who hold the fateful artefact under their control - well, I think that 4e does this more-or-less out of the box.I think the proliferation of Marvel universe movies is a glimpse into this mindset---the de rigeur line of thinking that the players are going to be the earth-shatterers, the apocalypse-makers for their game worlds. They're going to be the ones holding the "Tri-Force" at the end of the game and deciding the fate of the world. And if the story doesn't manage to TAKE their characters into that "superhero" space, that the "story" behind the gameplay is a waste.
And truthfully, I don't know that any RPG is up to the task of making that kind of storyline possible without a tremendous amount of GM force in the background.
(It'll take you more than 20 levels of play to get there, and the published modules won't help - you'll have to use the advice and the material published in the core books and supplements - but it'll do it!)
And for a game that let's you take this approach from the start (no zero-to-hero) there's Marvel Heroic RP - the Annihiliation Wars supplement was exactly this (if I've got you right).