Own player animations minecraft?

I'm currently working on my own Minecraft Mod and would like to create my own animations. For example, someone should stretch their hand up and then lightning will come.

the animations should be so that I can insert them later in MCreator.

Suggestion, use command blocks and watch "thejocraft videos" ;-)

If you have no knowledge you shouldn't answer… Command blocks can't modify the client, only mods can!

It is also about programming something and not doing anything with command blocks.