There are a LOT of tutorials for all the game engines. Just enter "engine_name tutorial" on for example Youtube's search and start learning. You can normally also find specific things you want to know about, for example if you wanted to know about making a VN in Unity you simply search
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But it is going to be a long process. You have a lot of different things to learn depending on which engine you choose.
Easiest would be,
Want to make a Visual Novel: use Ren'Py
Want to make a 2D RPG: use RPG Maker
Want to make anything: Use Godot, Unity, or Unreal.
Of course there are other that are easier or harder to use too. Game Maker, Visual Novel Maker, CloudNovel, etc.. Just use your favourite search engine with terms like "engine to make rpg games" or "engine to make visual novels", "engine to make 2D rpg games", "engine to make 3D rpg games", "engine to make point-and-click adventure games", etc etc etc..
Even the game engines like Godot, Unreal, and Unity have plugins which makes it easier to maek a specific kind of game. For Unity for example you get this really good Visual Novel plugin,
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and there are plenty more for FPS, 3rd person RPGs, 2D RPGs in RPGM style, etc.
It all depends on what you want to do and then look at what tools are available and what you feel will be easiest to work with.
Seeing as you are just strating you probably want to focus on free stuff for now rather than pay a bunch of money for plugins for engines so perhaps look into Godo since most things around it is open source and free.
Speaking of which, Github is also a nice source to find plugins for engines (which would be full source and free to use), for example searcher like this:
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