Hey Boop! I think there's 2 sides to your question. It's defenitely possible to create vfx flipbooks and or textures within after effects, however if you're looking to create textures of league specific style I wouldn't recommend it. We usually use hand painted textures within photoshop (95% of everything) or hand drawn flipbooks within something like flash, vs more realistic textures and flipbooks that you can generate with after effects. There's a lot you can do within a well drawn texture with alpha through scaling, squashing color shifting over time and erosion, for example.
Speaking on how to create effects within after effects I know there's a few plugins like "particular" and then using a flipbook generator to export for game use. So it's defenitely possible and perhaps others that have more experience with that could speak more on that topic. I have done very little VFX through After Effects.