The best approach would be if you have a look in the documentation.
It seems many beginners understandably overlook that, because while the term “documentation” is well established in software development, outside of that community terms like “handbook” or “manual” are more common.
So here is an overview of Engine Features in the documentation: Unreal Engine 4 Documentation | Unreal Engine Documentation
Another recommendation is to check out the learn-tab in the epic games launcher. There you will find the “Content Examples” project to download. Some pages in the documentation refer to it. Browsing and playing through its numerous commented demo maps for different topics is a big eye opener with many examples to dissect.
Cheers!