change vbox resolution code example
Example 1: virtualbox macos screen resolution
VBoxManage setextradata "High Sierra" VBoxInternal2/EfiGraphicsResolution 1920x1080
Example 2: how to increase the screen size in virtualbox
sudo apt-get install virtualbox-ose-guest-utils virtualbox-ose-guest-x11 virtualbox-ose-guest-dkms