I’ll start by plugging Harvard’s free courses catalog as well as Udemy
Edit: Gonna add 2 more I remembered-
Blender - I wish I had more time to learn it, but I did start the infamous “Donut Tutorial” once!
Watch Cartoons Online - Lots of good older stuff!
You should probably note, the functionality you’re describing now requires modding/plug-ins and not the “search and enable” kind, the download from third party sites and run random install scripts kind. It also since February requires you use your Kindle to download and copy every book you own (a chore if your family buys a lot of pulpy urban fantasy novels)