The best way to learn is to pick a project and build it.
There are lots of technologies to use, so my recommendation to just start building would be to use ViteJS, with React, and ESLint and Prettier. I might also recommend throwing TailwindCSS in there if it's not too much of a learning curve.
Theo recommends something a bit different that could also work: https://init.tips and https://init.tips/other
Apart from coding, I'd also recommend browsing sites like hacker news, twitter, and reddit. That, along with listening to podcasts or watching videos is a great way to get a better understanding of the frontend world.