I remember this 4 part series opening my eyes on a bunch of topics. I'm sure the 2022 10-part one is even more polished, though it's more than 30 hours of footage. Other than that when it comes to Unity specifically I'd suggest finding someone to mentor you in your next jams. I wish I had done that, because the only other way is trial and error. In regards to game design I need to reccoment "The art of game design" by Jesse Schnell. It is floating around the internet for free, but for legal reasons piracy is bad :)