How do I make the player transform?

Unity Engine
1

I’m pretty new to unity and I wanted to make a powerup that will transform the player. The problem is I have no clue where to start. It would really help me if someone would tell me how to do it. Thanks!
P.S: I’m coding in C#

2

show an example of what you want, from another game

3

like in super mario galaxy where yoshi can transform into blimp yoshi.

4

or in super mario bros where you can transform into fire mario or star mario where it changes your apperence

5

for that you make sprites with different colors and just change the sprites

6

How would I do that in game?

7

Or change the model?

8

use spriterenderer.sprite