In AOSP based android Q roms, there is a force dark option in developer settings whoich makes almost all apps to be appreaded in dark mode.
This option gets unselected after reboot.
One has to enable it after every reboot.
However it's possible to enable it by default after reboot.
For rooted phone.
Just add the following line in your build.prop file
debug.hwui.force_dark=true
Thats all.
It's working in my phone. Tested.
For unrooted Phone
execute the following line after reboot
setprop debug.hwui.force_dark true
To make it auto after reboot use tasker or script manager app or smthing similer.
Check the space after setprop and dark.
Hit a thanks to me if you are benifited.