Screen Size for Linux
Below is the command to run;
grubby --update-kernel=ALL --args="video=hyperv_fb:1024x768"
It works most of the time, but isn't guaranteed.
CentOS Settings related to the above command can be found in this file: /boot/efi/EFI/centos/grub.cfg
Sourced from here: https://www.netometer.com/blog/?p=1663