magnifico.... bro , you actually can ; when you're in HDR10 mode , go to video output settings and change it to SDR , then set up the HDR saturation from the imprex engine settings to your likings then go back to the video output settings and change the tv HDR mode to HDR10... you'll be on HDR10 with your HDR saturation level that you've chosen....
by the way , to change to whatever the TV HDR mode you like and keep such a mode even after rebooting, just go the system advanced options at the very bottom of the android settings list , not the video output options which will not keep the changes you made to the tv HDR mode after rebooting.
thanks bro