Struggling with Act breaks - How do you structure your script?

I'm deep in the in the trenches of my first feauture screenplay and I'm hitting a wall with act breaks. I know the general idea ( inciting incident, plot point 1,midpoint, plot point 2, climax) , but translating that into tangible scenes feels really challenging. How do you approach structing your script? Do you outline extensively beforehand, or do you discover the breaks as you write ?Any advice on making those transitions feel natural and impactful would be amazing. Trying to avoid sagging middles!