According to this Rotate Android display without changing orientation and this Allow rotate into portrait mode but do not rotate external display, I have to change some props value in build.prop file (using ROOT mode) to rotate output screen in HDMI monitor without changing device orientation. I'm trying to use portrait orientation of my Android and display it in full-screen mode on an HDMI monitor. On Android 10 and below, I've successfully rotated the screen, but what makes me confused is that on Android 11, this method is not working anymore.