When I began writing, the first structures I saw were generic guidelines about how to use theme, rising action, climax, and denouement (resolution).
Shortly after I began working with a few editors on a freelance basis, I heard about the “Save the Cat” structure. That’s a pretty cool format, and it helped me get a sense of what people look for — perhaps unknowingly — when they are evaluating whether a story is compelling.
It’s not a perfect structure or a panacea for bad writing or a poor concept, but it sure helps guide my own thought process a bit.
For an example, here’s how someone (or some group) applied the structure to Avengers: Infinity War. It’s a fun watch.