System Alert Window 

The following behavior changes apply to  all apps  when they run on Android 11, regardless of  targetSdkVersion.

To display overlay dialog on other applications or on system screen, you require  SYSTEM_ALERT_WINDOW  permission. This permission can be enabled from the device setting menu using  ACTION_MANAGE_OVERLAY_PERMISSION  Intent.

In Android 11: 

ACTION_MANAGE_OVERLAY_PERMISSION Intent will take user to common system setting screen, where the user can select which app allows to access system window.

In Android 10 and below: 

ACTION_MANAGE_OVERLAY_PERMISSION Intent will take the user to application setting screen, where the user can turn ON system window permission.

Exception:

For a few applications, the system will automatically grant permission using  ACTION_MANAGE_OVERLAY_PERMISSION.

E.g. Dialer application, Any app that is capturing the screen via a MediaProjection.