It's under two hours so it won't drag....
Less than 40 percent of the audience share for CA4 are women. Less than 30 percent from the tweens to 29 age range. I'd wager rough projections are close to 50 percent of the total audience is over the age of 45. Harrison Ford will give the film a little push with older demos, that's a given and the numbers show that, but that group tends to trickle across time. Most of the P&A budget is designed to support the film right at release.
There's a reason Chalamet and Zendaya were cast in Dune and given such prominent placement in the overall marketing. Even if , IMHO, many felt they were ultimately miscast.
The problem isn't making the film shorter, the problem is for this kind of financial outlay, they were better off making two Captain America 4 films. Once you had to truncate out Shira Hass/Sabra ( Israel/Palestine conflict considerations), removing Kang ( Majors scandal and ousting) and the politics angle ( need to shift out of the authoritarian "strongman" themes), what you have left are a collection of scenes. So work with that.
Eight half hour stories revolving around CA, Hulk and Ross would be easier to manage. Easier to get stunt casting and one off cameos. Easier on the editing team. Give Carl Lumbly and the Bradley/serum testing scandal it's own half hour block. Give him closure. If Liv Tyler shows up, give her her own half hour block, from the outside perspective of her fathers career and her relationship with Hulk. Even get voice overs from Evans and ScarJo to show the mission where Wilson breaks into the facility to get his flight suit during TWS. You aren't going to make another Eternals film, so give that cast a half hour to close out their storyline too.
If you don't have a film, then you have content. Two pieces of content are better for your bottom line than one of them. You make two distinct films, have it randomized which an audience will see, and allow them to view the other film via a voucher code through the Disney online platform.
Younger demographics are more likely to engage in shorter stories. You can't get back to the zeitgeist of Avengers Endgame, but you can tap into much of what makes "What If?" works and "Love, Death And Robots" work.