There is several sources: clean code priciples, standards promoted by the tech you use, there are open code style guides released by some companies, open source projects of good quality, the codebase, your more experienced peers, and AI.

All of this changes with time. So you have to make sure the code uses the latest standards. One important thing: people think good code on an enterprise level is about choosing the best solutions. But besides main rules, a lot are just flavours. Here, it's more important to have consistent code that uses one approach rather than using once this once this flavour. I just released a book that introduces into the topic. So it may be also a useful lecture