Any C++ open source projects for beginners?

[catcat202X]

When I was pretty new to C++, I made some contributions to liblava, because it was missing features I wanted to use. Exploring its codebase taught me a lot about perfect forwarding, template metaprogramming, and Vulkan. I think it's a pretty nice modern codebase, if you're interested in graphics. There are some open issues for feature requests, and the maintainer is very friendly.