A good place to start specifically for NetworkX would be to go through the new contributor documentation: https://networkx.org/documentation/latest/developer/new_cont...

We also have some structured projects https://networkx.org/documentation/latest/developer/projects... but they are usually for programs like GSoC/Outreachy.

Feel free to start a discussion https://github.com/networkx/networkx/discussions if you are looking for something specific :)

[I am one of the NetworkX devs]