How to make the character change to another?

I am trying to create a Ben 10 game.I want to make Ben change to Humungosaur when I press “Enter”. I have A Ben 10 3D model and a Humungosaur 3D model. Is there a script that I can use? Please help.

You can create them both at starting, but one hidding, when switching, hide the old one and show another. Try GameObject.SetActiveRecursively(visible)