Adding Camera Rig Switcher to VR Project

I'm pretty new to all of this unity XR and VR stuff so I've been working on this tutorial through Unity's Learn Premium platform which introduces beginners to VRTK functionality (https://learn.unity.com/project/vr-in-unity-a-beginner-s-guide?uv=2019.3). When testing the game, there's a starter UI menu that allows the user to switch the camera rig between a simulated one and a VR headset. (screenshot here: https://imgur.com/a/2lakBA9)

I am sharing the headset with other people, so I cannot constantly be testing with a headset. Therefore, this feature is ideal for implementing in my future project. My problem is that I cannot figure out where in the project that this functionality is added. Is it part of VRTK? Did the unity developers who made this tutorial create it themselves? I am trying to figure this out for the sake of replicating it but also so that I can modify the actual buttons used in the camera rig simulator (keyboard and mouse inputs basically).

This might be difficult to tackle if you, yourself, do not have the folder with all the contents used in this tutorial, so I understand that this might be confusing. If you don't follow the tutorial and downlaod the necessary contents, I think everything might be here (https://github.com/ExtendRealityLtd/VRTK/) since the scene used in the tutorial is located under Assets/Farm.

Any tips, pointers, or general direction would be really appreciated!