It’s not like there are much resources on this on Unity, or anywhere else really. I learned about making controllers from gameplay programmers at work in Epic Poland and CDP Red. And it wasn’t in “step by step tutorial” form, it was more like “first, you have to get the walking start angle, to know which walk start animation to play. You know, with trigonometry”. It took me three years of trial and error, to learn Unity and make a controller following these basic guidelines. The upside is that I fully understand now what is going on there and I implement new stuff without even thinking how.
Bottom line is - experiment and learn on your own. One on 50 things you try will work. Also, remember, that if you follow someone’s tutorial to the letter to make your game, you will end up with the same game as everyone else.