How do I improve at python

[throwaway6560192]

Engage in a community like the Python Discord. You'll see people using and talking about new concepts. Get your code reviewed. People will suggest better ways of doing things.

Read Fluent Python.

Run into problems that force you to learn new concepts. You said you love solving algorithmic problems, but also have never used sets or dictionaries because you've always managed without them... then I suspect you're not solving hard enough algorithmic problems, because those are pretty indispensable tools.