I actually really enjoy doing katas on https://www.codewars.com/, especially when I'm ramping up on a language.

You solve a short problem, and then immediately see how other people solved it. I'll frequently write something and then see a solution that uses a library function I wasn't aware of, or a solution that's similar but better follows the language conventions.

It's really helpful to solve something short and get immediate feedback on it. You aren't learning how to write big programs with the language, but it's still useful at first.