I developed a “test” for myself if I can play a song relaxed. I am currently revisiting the whole course after finishing to clean up technique/get more relaxed and get used to a different position of the bass which I changed in the slap module and found if I can play something while walking around/in circles at the same time I can breathe and relax. I think there’s a zone in there for learning new things in which you can not be totally relaxed but not so overwhelmed as to not reach the state at some point in the future.
I don’t really have any tips to reach the relaxed state though. When learning something/new harder I think it just takes practice in the zone I was talking about until you are able to. And of course rule #1 as I call it from now on: learn to play slow. Get faster later.