For VR apps, Unity provides three rendering modes: Multi Pass, Single Pass, and Single Pass Instanced. This can be configured under Edit | Project Settings | Player | XR Settings | Stereo Rendering Method (note that the checkbox of Virtual Reality Supported must be enabled for this to show up):
Multi Pass rendering will render the scene to two different images, which are displayed separately for each eye. Single Pass Stereo rendering combines both images into a single double-width render texture, where only the relevant half is displayed to each eye.
Note that XR Settings are enabled only for ...
