The EF-S to RF adapter is only possible because of the very short Flange focal distance of 20mm of the RF mount compared to the 44mm of the EF and EF-S mounts.
The adapter places the EF-S mount lens at it’s native 44mm distance from the sensor, so the image is no larger, and there will still be severe vignetting with crop lenses.
Canon RF mount cameras will automatically crop the image from a Canon EF-S lens, while Third party lenses do not.
When using a third party APS-S lens like Sigma, Tamron, or Tokina, it is possible to select a manual crop mode with RF cameras.
