This is a paid asset, but now you can download Fullscreen Editor Free.
Detail this asset from Unity Asset Store: Original Link
Fullscreen Editor v2.2.3 (Latest version)
Fullscreen Editor v2.2.2
Fullscreen Editor v2.2.1
Want to play your game in fullscreen without building it? Want to edit your scene in fullscreen?
Now you can!
Contact | Website | Forum Thread
• Plug ‘n’ play, it works out of the box
• Better performance since version 2.1.0, no more framerate drops!
• Multi-screen support, use as many monitors as you want
• Fullscreen on play, because maximize on play is a waste of space
• Configurable to best fit your needs
• Non-intrusive
• Fullscreen for any window, even the whole editor
• Keep the state, don’t lose changes made on the fullscreened window
• Clean code
An extension that does what its name says, it puts editor windows in fullscreen mode, simple and easy, useful for recording, testing in a real gaming environment and tweaking your scene.
Everything is still fully functional in fullscreen.
How to Use
Simply press the shortcut to fullscreen a window or close it, defaults are:
F9 for any focused view;
F10 for game view;
F11 for scene view;
F12 for the main view.
These shortcuts can be changed anytime in the preferences menu.
Supported Platforms
• Windows: All features available, out-of-the-box multi-display fullscreen.
• macOS: Not tested on multi-display setups.
• Linux: Requires wmctrl to be installed and a EWMH/NetWM compatible X Window Manager. Has some features limitations.
Supports all Unity versions since 5.6.
Source code included!