Set Monitor DDC Brightness/Contrast + Extra Dimming

Installation and Configuration

Install ddcutil

sudo apt install ddcutil

Make sure i2c-dev is loaded

After installing ddcutil, make sure i2c-dev is loaded:

sudo modprobe i2c-dev

or add i2c-dev to the /etc/modules file.
(More info: https://www.ddcutil.com/config_steps/)

Add your user to group i2c

sudo usermod -aG i2c $USER

(More info: https://www.ddcutil.com/i2c_permissions_using_group_i2c/)

You can check if its working by trying:

ddcutil detect

More info:

https://www.ddcutil.com/install_config_main/

Install this GNOME extension

Last but not least, get this extension here: Monitor DDC Brightness/Contrast + Extra Dimming
(Also available from your Extension Manager.)

Log out / Log in

You need to log out/log in after doing all the installation and configuration procedure for this extension to work.