>>149832338
The actors are told what needs to happen in the scene so the outline says:

SHIELD LAB DAY 1-2 minute scene
Reed, SmartHulk and Ironheart and any other 'science' characters discuss scientific options to fix the multiverseal incursion. Reed mentions that he teleported his Earth, SmartHulk says how they used time travel to beat Thanos and Ironheart compares them to incels using cheat codes on a video game. This inspires them to use the [unnamed Mcguffin device].

The actors just improvise their dialog from there as long as the scene accomplished what it's supposed to do. It's basically how Christopher Guest makes all of his Spinal Tap type films and in a weird way it's not unlike the classic 'Marvel Method' of doing comics.