How to change the field of view

I am developing an AR application for Xreal Air Lite using the NRSDK for Unity.
I wold like to change the field of view of the NRCameraLig cameras while it is running, but when I set the fieldOfView value, it is ignored.
How can I change the field of view?

Hi, the hardware vertical FOV and horizontal FOV of the glass are 22 and 40 degrees, the virtual camera in Unity cannot exceed the limit.

Understood. Thank you.

fwiw, you technically, CAN force the .projectionMatrix value of the camera to something, but as XREAL-dev mentioned, this is not recommended and will have other side-effects