With all the migration from VMware to other sources, Hyper-V is making quite a comeback. Hyper-V is a lot better than the good (aka bad) old days, but you still need to know how to handle certain quirks.
In this case I needed to change the resolution of my Hyper-V windows guest to something higher as it was stuck on the default 1152×864.
It’s simple to fix, just shutdown your VM in the Hyper-V manager (or use powershell) and when the system is down, open a powershell window and use.
Set-VMVideo -VMName "<Name of VM in Manager>" -HorizontalResolution 1920 -VerticalResolution 1080 -ResolutionType Single
Then when you power the VM back on and access via the Hyper-V display option you will have a VM with the larger screen resolution.