Simple Gnome extension that adds a toggle icon to the dash to change the display scaling of the primary monitor between 100% and 200%.
This extension requires python3 to be installed. This will hopefully change in the future.
For manual installation copy all files to ~/.local/share/gnome-shell/extensions/scaletoggle@t-vk.github.com. Then reboot or log out and in again.
Note: In more recent versions of Gnome, this extension does not seem to be wokring anymore. Further investigation is required.