file format – What is the process used to create these "vector" art games?

I appreciate the artistic styles of games like magikarp jump, postknight, hunt-cook: catch and serve, puyo puyo tetris etc. images.

Specifically, I would like to get a better idea of ​​what the process of creating, animating, exporting, importing, optimizing, and rendering art assets, as well as the formats file, artistic creation tools and development tools. For example, should I just use a vector design tool and not use a raster image editing tool?

Any idea would be very appreciated.