In Unity, the camera you view the world through has a set minimum and maximum rendering distance. This is because having a smaller minimum and maximum to render lets it be rendered with more precision. Setting the maximum too high or the minimum too low will result in flickering known as Z-fighting.

The range between this minimum and maximum is known as the view frustrum, and that minimum and maximum are the Near Clip and Far Clip respectively. This terminology stems from how the viewing range of our camera is a pyramid with the start and end cut off. The area left behind is called a frustrum.

IMPORTANT: You MUST have a Main Camera in your scene, set as the Reference Camera in the VRC_Scene Descriptor.

While not necessary, it's recommended to place your main camera in the scene somewhere where you can view the effects of the distance getting cutoff. (You can align it with your view in the Scene window with Ctrl-Shift-F.) That way, you can switch to the Game window to see exactly what effect your changes have.
From the properties of your main camera, you can adjust the Near Clip and Far Clip values.

• Near Clip defaults to 0.3. Objects closer than this will be clipped away. Lowering this will allow objects to get closer to the camera. Raising this is not recommended.
• Far Clip defaults to 1000. Objects more distant than this will be clipped away. Raising this past 3000 is not recommended.

Change these to suit your scene. Make sure the camera you've adjusted is set as the Reference Camera, or the changes will not appear ingame.

https://docs.unity3d.com/2018.1/Documentation/Manual/class-Camera.htmlhttps://en.m.wikipedia.org/wiki/Viewing_frustumhttps://docs.microsoft.com/en-us/windows/win32/direct3d9/viewports-and-clipping