Create Side Scroll Scenery in 2D

Hello, I want to create a game where the scenery will be all handcrafted in 2D as shown in the reference image:

I did a lot of research on the subject on the internet and I only saw tutorials creating sprites in Pixelart but my game would be a more freehand illustration and I don’t know if I would do the sprite I believe there is another way, I was watching this video tutorial here:
https://www.youtube.com/watch?v=g31NTpq9p-o&t=186s

but I am very doubtful if this is really the only option to create a 2D scenario.
My game reference would be the grand Chase it is a KOG game with a fully 2D scenario and the enemies / characters are in 3D and I will follow the same model for my game follow the image of the game:
image

So my question is if there is any tutorial or documentation that shows me if there is any other format to create 2D scenarios other than in pixelart since from what I could see this format of creating scenarios with sprites is more applied to projects in pixel art