How to get 4k Video from 823a and 811a on my Monitor?

Hi Guys!
I am just wondering, why Reolink dont support 4k Video at their own App.
YES, i know, if i watch the single Cams clear (4k) View is available.
"Sad" Part, I have 5 Cams and want to watch them at same time.
So at grid View, the Cams only support a low resolution.

Is there any other App which support 4k Video for 5 Reolink Cams at same Time View and dont cost 1000 of EUR ?
VLC is not really an option btw.
It would also be nice to be able to adjust the Picture of the Cam, even if its not 1:1, because 5 Cams on one Screen is tricky, if you cannot change the size of the Picture.