Make a sprite sheet

So i created an avatar on which is really create for creating 2D avatars and i exported them into a .Zip file then took them out and put my avatar in unity. My avatar is 4 separate sprites at the moment and i was wondering if theres any way to create a sprite sheet for my avatar or is there a way to use the animation function in unity to switch between the images i want In-Game

There is, read the Unity documentation.

Yes its called the Animator (read up on it if you don’t know what that is…)
To create and Animation for the Animator Controller

  1. Select the Images
  2. Right Click > Create > Animation

all your images should now be as an animation…
this is a very basic procedure.

let me know if this helped