Controls the actual size of eye textures as a multiplier of the device's default resolution.
A value of 1.0 will use the default eye texture resolution specified by the XR device. Values less than 1.0 will use lower resolution eye textures, which can possibly improve performance at the expense of a less sharp image. Values greater than 1.0 will use higher resolution eye textures, which can potentially result in a sharper image at the cost of performance and memory.
This will always reallocate eye textures, which can be an expensive operation. For dynamically changing eye render resolution on the fly, consider using XRSettings.renderViewportScale instead.