Hello there,
You're generally limited in choosing a resolution based on the resolution of the underlying operating system on which the virtual machine is running, so you may need to increase this to maximize your VirtualBox Display Resolution. You can also adjust VirtualBox's settings to give more video memory to your virtual machine, which may enable its operating system to output higher resolutions. To do so, click the "Screen" tab in the VirtualBox Settings menu and set how many megabytes of video memory you want to allocate to the machine.
The Set-VMVideo cmdlet configures the video settings for virtual machines. https://learn.microsoft.com/en-us/powershell/module/hyper-v/set-vmvideo?view=windowsserver2022-ps
Hope this resolves your Query !!
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