Installing GNOME extensions
GNOME extensions add various functions and tweaks to the GNOME Shell which is the default Desktop Environment used by Ubuntu 17.10 and later.
Extensions can be found on the https://extensions.gnome.org/ website.
1 Using Google Chrome/Chromium
Open the GNOME Launcher, click on Terminal and type in the below command:
sudo apt install chrome-gnome-tool
2 Using Firefox
3 Installing Extensions
After completing the above steps for your browser, explore the extensive library of extensions.
When you find one that you like, simply click the On/Off switch to turn that extension on.