Thank you,
editing build prop in android 10 seems to not work, at least it wont stick on reboot,
magisk module
MagiskHide Props Config seems to be able to make youtube think it is 4k , i can select up to 4k in youtube now..
However, when I make a screenshot, i thought, i might be able to compare the screenshots in different youtube resolutions, i get 1080 x1920 screenshots. so that won´t work. maybe youtube does 4k and the rom scales it back to full hd or the screenshot app is only able to do 1080x1920...
I had tried some resolution changing apps e.g.
this one , but the thing is only the top left 1080x1920 of the display is then touch responsive... If you are not carefull you cannot get it back to normal. With a bluetooth mouse (and possibly keyboard) pre-connected you can go over the whole screen though.
of course this is all in pixelexperience + and i had not tried all of this on the stock rom, i have this phone recently and found pixelexperience + very soon to be the way to go, my experience with roms is stock , stock + magisk, and usually i used existenz on xperia z.. or xz.. series. not for this phone though..