This simple tutorial shows how to auto-hide the top bar in Ubuntu 18.04, Ubuntu 19.10 with the default Gnome desktop.
It’s easy to enable auto-hide the dock (left panel) feature as Ubuntu offers an option in the system settings utility. To run any maximized application window in full-screen like a video player does, you can also make the Gnome top bar auto-hide.
This can be done by a Gnome Shell extension called ‘Hide Top Bar’.
Open Ubuntu Software, search for and install
hide top bar gnome shell extension.
Once installed, launch the extension settings either from Ubuntu Software in the install page, or by going to Gnome Tweaks -> Extensions.