I found this online video course by Kent Dodds Advanced React Patterns 🔥 as well as reading through the Advanced Guide Section of the React Docs 📄 helped sharpen my React skills 💯.

There is a course on udemy named "React Native Advance Topics" by Stephen Grider. It's the best.

https://reactresources.com/

You can find anything you want, courses, articles, projects, etc. Enjoy.

If you prefer to learn by reading articles and stuff then I'd suggest you to checkout Advanced Guides section in reactjs.org. It covers almost all advanced topics in React with a detailed explanation enough to introduce in your code to play around.

Also, don't forget to follow the blog called overreacted.io written by Dan Abramov, one of members in React team. He writes amazing blogs on internals and super advanced topics on React and UI concepts.

If you're a video person then I'd suggest you to checkout frontendmasters.com, contains advanced topics in React, although its a paid one but worth it. Taught by highly respected people in frontend community.

Cheers!