Draw something you personally enjoy first. Doesn't matter if it looks bad, just start at something. If you like to draw cute anime girls, you should. Once you feel like you are hitting your limitations or want to improve more, then it's time to study masterworks. Or if you want a full schedule...
I'd recommend using NRP_GameWindowSize plugin. It allows you to magnify the game window. You'll still need to redo your menus to accommodate the small size, though because RM has hardcoded values on some areas. OMORI menus are custom made so they adjust nicely...
Still one of my favorite scripts that I may or may not be using in MZ.
Script Calls for those who need it.
// Make Player go to X/Y
$gamePlayer.setTarget(null, X, Y);
//Make Player go to target event
const target = $gameMap.event(ID)
//Make event go to target...
Making assets take so long to do from scratch that yeah it might be worth looking for an asset pack as close as possible to what you want and expand on it instead.
IF you are making pixel art assets from 100% scratch, I recommend looking at Lospec and look at some palette for starters. One of...
parallax mapping won't save you from level design. I even highly suggest against it because of the amount of memory leaks you'll have to deal with later. Try pairing up with a mapper or look at some maps to get inspiration mostly. (I hate mapping too, I feel you. I like making tilesets though)
Here you go straight from Harvard University. It's pretty hard but worth it.
Learning Computer Science concepts is as deep as you can get.