Oddly enough, I benefitted from interviews early in my career - engineers probing for my knowledge boundaries would usually find some technical questions where my knowledge was weak, so I'd make a mental note to learn about that thing later.

Figuring out flaws in your development process can be harder, but it's worth asking for coworkers/manager for insight, they can often see what you don't even think about.

In terms of improving comfort and knowledge of new tech, I do personally projects and try to incorporate one new tool, language or framework every time.