>>272427236
I've heard the default faceplate on Rift S reduces the FOV a lot, so try taking it off to see how much difference it makes. If you still consider it too narrow, Index isn't going to make a significant difference. The maximum each headset renders horizontally* is 110 for Rift (CV1) and 135 for Index. 25 degrees is only 12.5 degrees on each side, which isn't a huge amount.

*calculated by the camera FOV in Unity, which is what each eye renders (96 for Rift, 110 for Index), then creating a composite image (pic) of both eyes and measuring the difference between the single eye and combined widths. Index has a wider aspect ratio.