How to make animation for a character without them already?

Unity Engine
1

So i want to make a game where it is possible to have different knife animations and such, but there is some minor problems…

I dont know what you other game creators do, but i only use assets from the asset store, is that normal or should a coder be able to make his own props and such?

And next question:

How do i add animations to a character a found on the asset store who doesnt have any animations already?
like if i wanted to add a knife animation or running animation?

2

If you don’t want to make animations yourself
you could get/buy muscle clips (or you could call Humanoid animation) from the store.