sketchfab 3D models (or even just a hat in person) can allow you to observe the depth of the hat and when things end or start, or even the angles things go up like a cap's main part of the hat, maybe even the duckbill-like angle that the cap's bill (literally that's the name)

some people (like myself) just draw perspective from instinct cause the calculations take awhile, but a really well proportioned hat in perspective is the most satisfying thing ever when it's done right

I don't but you could probably simplify it to how shapes look, the bottom surface is the one being angled, then you draw it as if there were an axis in the middle that decided the top of it, then draw around it since most hats are circular and are pretty much identical throughout the hat. like starting with a pancaked hat, that you push out the inside of so it takes form.. and with a Fedora or something, make it a square plane and draw a proportional oval in that space, and put a box on top that helps you angle the unique boxy shape