Regardless of what his title will be, Steve Rogers, aka Captain America is technically the King of Asgard.
If theories are to be believed, Thor had, in a drunken state of mind in Avengers: Age of Ultron promised to give this kingdom to Rogers.
Marvel Fan Points Out the Reminder:
As a die-hard fan of the MCU frequently pointed out, Thor was in full agreement with the group that there should be someone to lead Mjolnir, and this person would also be the rightful heir to the throne of Asgard.
As evident in Endgame, Rogers had eventually succeeded in wielding Mjolnir to help save Thor from his death by Thanos.
Soon after the film was released, Joe Russo, the film’s co-director, had said in an interview that Captain America was capable enough to pick up the mentioned hammer in Age of Ultron.
He also said that Rogers did not do so because he didn’t want to embarrass Thor in front of everybody.
Additionally, every Marvel fan has, at some point, believed that Cap was worthy enough to potentially lift the hammer and the day he did it would be extremely special.
The Build Up to The Scene:
Ever since the movie was in its early stages of production, the moment where Cap grabs the hammer was something that the makers of the film wanted to stress upon.
This would also portray Cap’s journey throughout the films.
It would also be able to successfully show the multiple inner layers that Captain America’s character eventually has.