How to make 2 different character switch in the same scene and also rigs possible?

I’m not very well at explain. But How do if I want make 2 different head switch in same scene. for example, One head for human, other head for monster. switching on and off, So that I want make look like he transform into monster. Also, Is this possible for rigs to link or something in same scene? I don’t know, I’m not sure how to do this. but you can click this video for example. https://youtu.be/6xr_9Ce2Ylc?t=137