Use APKPure App
Get Navigation Bar Hider old version APK for Android
Hide navigation bar/soft keys.
*Require ADB or ROOT*
[What is this again?]
This is an app that modifies hidden policy_control settings to hide the navigation bar.
[Why would I do that?]
I don't know.
[How do I use it?]
You will need a computer, and following the instruction here:
https://github.com/TsFreddie/EssentialLayoutWhitelist