Creating virtual enviroment with x-y direction

Hi y'all, Stupid nood here..

I am an architecture student, having basic knowledge of programing in unity (but not going to give up). I am curious about some things, just to find the direction to work further on my thesis. One of the troubles is i don't know the terminology for the addressed issues so sorry in advanced for any stupidity XD

1. I have worked on 360 animated videos (not with unity) (here is one example :

). The camera is moving on a certain path and the viewer can move the head up down and rotate (either with vr headset or with gyroscope phone).
So the question is : Is there a way to move on x-y direction without the pre-designed path of the camera? I am suspecting it would be 3d enviroment live action?! I don't want it to be necessarily merged with the real world (i have seen AR tutorials but haven't find sth similar) But i would love to "snap" it in specific coordintates (or "pin it", thinking like pokemon go gyms, where every player get to see the same gym on the same coordinates) . (for example put a whole room with an enviroment like the one above in a specific place and you could watch it either with vrheadset or with simple phone screen)
P. S. No use of controller or buttons wanted. Just a "walk through room" kind of thing

2. So the second question follow-up of the above is: wanting to be multi environment "scenes". Is there a way that things could change so dynamically without buttons? I thought of it as levels and the trigger would be time. But could it be like a nice transition or only fade in / fade out. (again i have searched for tutorials and found some cool stuff but not quite the direction)

3. And the final question is : Can one use in unity dynamic materials (such as rainbow changing colour surface or whatever)? I mean this could be a way of scene transition tool but still just throwing ideas.

Sorry for the long post and the unmatched questions. Any tip or pointing direction would be a Blessing.

Thank you in advance