LG C4 questions about Dolby Vision IQ and Peak Brightness

A technical question: I have a 65-inch LG C4 and I wanted to try Dolby Vision IQ. As far as I understand, to activate it you need to select Home Cinema mode and enable AI Brightness.

From what I've read, Dolby Vision IQ adjusts the brightness based on the room's ambient light. However, when I turn the lights completely on or off, I don't notice any change.

1. Does the general light sensor control (which I currently have disabled) also need to be activated for Dolby Vision IQ to work properly?
2. On the other hand, does the Peak Brightness option limit the maximum nit output? If it’s disabled, does it play content using the original nits from the film? What exactly does this setting do from a technical standpoint?

Thanks in advance.