Install gnome-shell-extension-autohidetopbar by entering the following commands in the terminal:
sudo apt update sudo apt install gnome-shell-extension-autohidetopbar
Description:
GNOME shell automatic topbar hider
This gnome-shell extension automatically hides the topbar, except in overview. There is also an option to show the topbar when the mouse pointer approaches the edge of the screen. . Please note that you have to manually enable the extension, for example using gnome-tweak-tool.
Homepage: https://github.com/mlutfy/hidetopbar
Version: 20171126-2
Section: universe/gnome