Yes, loads; but without knowing what kinda stuff you want to learn to do, I wouldn't recommend anything in particular

Edit: might as well give some ideas though... Some libraries such as http frameworks will have some examples projects that use it, sometimes even in the core repo under ./examples or something. There are lots of small personal projects from random GitHub users that you can stumble across. Many useful and well written libraries are small enough to be approachable. But which of those to recommend depends on what you want to do with your code.