I saw a video of a daredevil who decided to film himself hanging on to the roof of a skyscraper with his fingertips. He did a couple of pullups, but exhausted himself and could not pull himself up back onto the roof. Finally, he let go.

Pulling oneself up onto something by one's fingertips takes a lot of strength. Should have tried that beforehand. (It looks easy in the movies, but those stunt people are very fit.)

Those stunt people also use special effects to make it look like they are on a building but really a padded floor is just below their feet. If you only can see their upper body it may be they are standing on a stool or someone is pushing them up (though in this case I would expect they are actually pulling themselves up with brute strength). They also do this stunt a dozen times and then in editing choose the cut that looks best.