A320/B737 documentation

Hi there! I'm a commercial pilot with interest to get to know how the A320 and B737 work. I've been trying to look for online manuals or videos to get to understand how the systems work in both aircraft but all I get are recommendations for Type Rating courses (which are something I'm not aiming to do in the short term).

Does anyone has any documentation/videos that explain or detail how the systems in these aircraft work? Any suggestions are highly appreciated!