If you want to learn JUCE, one of the best things you can do is clone every single repo in Sudara's wonderful juce-awesome list, and every week do a mass update of the repositories - you will learn a lot as there are some projects which really push new updates hard each week, and just learning what was committed will give you a great path to learn things ..

https://github.com/sudara/awesome-juce

(Direct link to the raw data here: https://raw.githubusercontent.com/sudara/awesome-juce/main/s...)

Some truly wonderful things in there to learn from - starting with basic plugins, all the way up to synthesizers and a full DAW. Be sure you mine that resource!