So I’ve wanted to get more into making materials because I really think it’s fun. That being said, I have watched Epic’s tutorials and also looked through the documentation but I kind of feel like I am stuck. Are there any good in-depth tutorials that more advanced materials, for example (but not limited to) realistic looking water or really fancy stuff like )
Check UE4 Demos and inspect the shaders. There is much!
Also check out guys downloadable project that shows how to create just about any material you can think of, I downloaded it morning to take a look, and it is a great resource for understanding how materials work, and the amazing things you can do with them!
https://forums.unrealengine/showthread.php?55336-(Update)-Project-MaterialLab-with-Community-Beta
Also take a look at videos from Hourences: ://www.hourences/thesolusproject/ 
+1 for pmlvl suggestion -> best way to learn how material work + make sure that you also just try some stuff by your own
Thanks for the suggestions!