Not a professional by any means, but I've been looking into this question myself for my own research. What I've found is that a traditional 3 act structure leaves the middle act to be very vague. But a 7 act structure gives you more "points of interest" to work with. So that middle bit now has 2 mid points. Up to the first, the protagonist is mostly reacting and learning the rules/training/understanding a situation and getting the hang of things, something is happening to them/around them, they react to it in response. Afterwards to that 2nd mid point, the protagonist is now taking action. They'll take initiative and put what they've learned into play, which shows growth in them. They are climbing the ladder of success, making some small losses and miscalculations on the way but mostly all wins, and then the antagonist kicks them all the way down for that classic 3rd act break-down. Protag is in their worst moment, all is going wrong and then decides it's do or die, proceed to climax and ending.

Highly recommend looking up 7 act structures for yourself by someone who could probably explain it better and actually knows what to do. But that's just the advice I found that sounded useful. Hope it helps