Field of View (FOV) must match the device: The FOV value is set through the device’s SDK and internal configuration, and matches the physical geometry of the headset and lenses. Because of this, the FOV should not be modified in UE, and should not be modifiable by the user. If the FOV value is changed, the world can appear to warp when you turn your head, leading to discomfort.
The only way would be to overwrite the source code or write your own camera component.