How to grow beyond early intermediate stages?

I’m a relatively new developer, I didn’t have a clue how code even worked about four years ago when I discovered an interest and gradually started absorbing. I’ve never a formal class on any of this, but I was lucky enough to find work at a company that doesn’t use “top of the line” tech. We’re a very small team of mostly older engineers that I’m actually able to contribute some slightly more modern conventions to. I’m wondering what is next for me as I’m worried about not learning enough where I am now. I think I want to contribute to some open source projects but I have limited experience adding to other people’s code, almost none if the project is large. I also only have a slight grasp of OOP (primarily use python where you can sometimes program without noticing how many objects you’re using), thinking about learning Java so I’ll be forced into OOP exposure.

TLDR; fundamentals are good and I’m mostly out of tutorial hell but it feels difficult to keep improving myself with my limited dev experience, how to push through?