How to set secondary screen as default for mirror mode?

I have a rooted LG phone running android 12. There is screen+ feature in LG like samsung dex that gets activated only when connected with usb to monitor. But when I connect via wifi to any display device for screen mirroring, only main android screen is shown. I want to mirror only secondary screen i.e. screen+ desktop. Ticking force desktop mode in developer options did not help. Is there any way to set screen+ desktop as a default screen for mirroring by making changes in android system settings ?