I encountered this metering selection mechanization a couple of days ago. I am using the RC-N1 controller with an iPhone and the DJI Fly app. All SW and FW is current. (Mavic 3, non-Cine.) If you guys already know this, please be gentle. 
But I see no reference to it anywhere in the user manual.
You can experiment with this with the aircraft on, connected, camera view. In PHOTO mode, simply select somewhere on the screen (somewhere that doesn't invoke another function). You'll see a small highlight cube, with a "sun" symbol to the right. This cube is the light metering selection. You can change its location by selecting somewhere else on the screen. The selection will be disabled if the camera view moves beyond the selected area. (I think it also auto-disables after a timeout, maybe 10 seconds?)
This selection behaves as a small area light meter - not exactly spot metering, but not bad. It's very helpful if you are taking photos in high-contrast environments and need to select the area used for exposure.
I don't think this has been covered elsewhere - if so, my apologies.
But I see no reference to it anywhere in the user manual.You can experiment with this with the aircraft on, connected, camera view. In PHOTO mode, simply select somewhere on the screen (somewhere that doesn't invoke another function). You'll see a small highlight cube, with a "sun" symbol to the right. This cube is the light metering selection. You can change its location by selecting somewhere else on the screen. The selection will be disabled if the camera view moves beyond the selected area. (I think it also auto-disables after a timeout, maybe 10 seconds?)
This selection behaves as a small area light meter - not exactly spot metering, but not bad. It's very helpful if you are taking photos in high-contrast environments and need to select the area used for exposure.
I don't think this has been covered elsewhere - if so, my apologies.
