How do i change SpriteRenderer.Sprite

language doesn't matter in this case. if i give you the direct answer you wont learn from it. this is something quite simple. but you need to learn how to get components from other objects/scripts.

i don't really like java. its quite messy in my eyes. so il just give you some sudo code. you can convert this easily to your syntax

 // better if its in a list or array but this will do fine for now
 public GameObject sprite1;
 public GameObject sprite2; 
 
 gameObject.getcomponent<spriteRenderer>().sprite = sprite1;

Found it my self thanks for help:

var sprite1: Sprite;

GetComponent(SpriteRenderer).sprite = sprite1;