I’m using Android 13 Google AOSP.
In Settings -> System -> Gesture -> System Navigation, neither Gesture Navigation nor 3-button Navigation works.
Gesture navigation works normally, but the bar is not visible,
The 3-button navigation is not visible in both the function and UI.

I think this is a problem because my device is small in size compared to other devices.
Switching between each feature is normal, and I don’t know how to fix it in the system UI or launcher 3.

I’d like to know a detailed solution.

When I checked the layout range of the navigation bar in developer mode, I confirmed that layout space is being allocated.

The navigation bar layout area seems to invade hotseat, so even if you add the bottom margin value of hotseat and modify it so that it does not invade the area, the result was the same.

It was useless to change the navigation_bar_height value to 48dp -> 24 dp in the framework.

In NavigationBarView.java, only layout space was assigned to the location even if the location was modified to bring the location of the navigation bar to the center of the screen in the onLayout method, and the actual bar was not visible.