Android 10.0 SystemUI sets the navigation bar to default to system gesture navigation

In the 10.0 system, the default navigation bar is three-button navigation, and the three buttons of the Home Back Recent button are displayed at the bottom,
but for some full-screen apps, it feels inconvenient to operate, so the customer requires the use of system gesture navigation. At this time,
the bottom of the system is won't be occupied

How to set the system gesture as the default navigation method? The
first step is in config.xml

The path is: frameworks\base\core\res\res\values\config.xml

 <!-- Controls the opacity of the navigation bar depending on the visibility of the
         various workspace stacks.
         0 - Nav bar is always opaque when either the freeform stack or docked stack is visible.
         1 - Nav bar is always translucent when the freeform stack is visible, otherwise always
             opaque.
         2 - Nav bar is never forced opaque.
         -->
    <integer na