Ojika
After changing the DPI of the system
If you set the application to be in picture in picture(PIP) mode, the DPI of the application is fixed and unchanged.
If you open the app separately and display it in full screen:
The DPI of the system interface you usually see and the built-in application interface of the system are fixed and unchanged.
We cannot control the DPI of other applications, which are controlled by themselves. Some applications, such as Waze, may change their DPI with ro.sf.lcd.density, while others may not change their DPI either.