How do I use Mac's brightness controls on external display?

[jas9]

So guys I have set up an external display with my MBP. Here's what I want it to do now.

I want to use only one display at a time. So when I plug in the USB C cable, I want the external display to take over. When I unplug it, I want to go back to MBP's screen. When I am using the external display, I want the MBP's screen to turn off (right now I achieve this by taking the MBP's brightness to zero). But I want to be able to control the external display's brightness with the F1/F2 keys on the MBP's keyboard. Its a big hassle using the external display's brightness controls. Please note I am using a USB C to HDMI adapter to connect the MBP with the external display.

1. Plug in USB C and external display takes over and MBP's screen turns off. Take it out and MBP's screen turns on.
2. F1/F2 brightness keys should control the external display's brightness.
3. I have no desire to use both screen's at the same time.

How do I achieve this?
Thank you!

 

[Darth.Titan]

The external display’s brightness is controlled by the buttons on the display.
The brightness on the laptop display is controlled by the keyboard buttons.
There’s no way for your laptop keyboard to override the hardware controls on the external display.

 

[jas9]

Ah, okay.

The external display’s brightness is controlled by the buttons on the display.
The brightness on the laptop display is controlled by the keyboard buttons.
There’s no way for your laptop keyboard to override the hardware controls on the external display.

Ah, okay. But can I do the other thing (point 1)?

 

[hobowankenobi]

Last I checked, you can close the lid on portable, following specific steps.

I don't have a second monitor handy...can use the brightness inside System Preferences/Displays? I don't think so, but worth checking.

If you fiddle with resolutions or other settings, Display Menu is super handy. Even the free version is very useful for second monitors (assuming you were using both).