To limit fov so it does not go below 90, you first redefine the slider range so you map 0-1 to 90-120.
(See blueprint WB_ClassicSettingsVideo -> Event Graph)
Then, when slider is updated, scale needs to be remapped from fov to 0-1
(See blueprint WB_ClassicSettingsVideo -> Refresh Field Of View)
User can still override this if FOV is manually typed in text box.
If you don’t want user to be able to type in extreme fov values, you have to update clamp range in BP_GameSettings -> Set Field Of View
The unreal engine Cinematic mode is not designed for real time gameplay. It is for offline rendering.
The quality values ranges from 0 - Low, 1 - Mid, 2 - High, 3 - Epic, 4 - Cinematic.
When I made the settings menu, cinematic mode did not exist, so the values are currently locked from 0-3.
Going over the functions and allowing values up to 4 should work, and I can add that in a future update so it is more accessible if a developer wants it.
Cinematic mode is not optimized for gaming, so you should avoid it by default.