@lizardsquid if you want to take a low level approach, i recommend skimming through handmade hero. it's a video series where a game engine dev walks through development of a simple 2d and later 3d game but without using any libraries, so he has to dig down into every topic that you might need to know about when writing an engine yourself:
you don't need to watch every episode (there's a ton!) but if you're confused about a topic then it's a handy reference