Well, you can see quite a lot of amazing games being built on our Demos and Projects session: Latest Demos and projects topics - Babylon.js (babylonjs.com) so it’s certainly possible to make all kinds of games.
Visually, @Lun has made incredible toon shaders that look like the Genshin ones: Genshin Toon Shader Babylonjs NodeMaterial - #13 by Lun
No matter what the approach you take, however, making a game requires a lot of patience and dedication, so you might want to start with simpler games before attempting to make something as ambitious as Genshin, which is developed by hundreds of people 