Create a small project to teach yourself. Whatever is most interesting to you. I created many things because I wanted to learn something. Most are not available, but for example I made https://13vaults.com/ from scratch to see if I could make a DnD Beyond clone. It isn't small, but it was a personal challenge I set out for myself just to see if I could do it, and my players hated the 13th age online srd.

I made https://fotup.app/ to learn a programming language (ReasonML) and because I needed a way to upload images with my clipboard and getting a URL. 13V is still working but I used a third party API for fotup and it stopped working so it's borked. But I got all I wanted out of it!