You can disable the internet connection or set up a virtual network adapter for a VM in the Host Only mode to allow network communication only between host and guest systems, and deny connecting the Windows 10 guest to external networks, including the internet. If security is a concern for you, running Windows 10 as a virtual machine (VM) on VirtualBox is a good idea.

How to Make VirtualBox Full Screen for Windows 10 Guests Don’t worry, as it is possible for you to increase the screen resolution of the guest OS user interface as well as run a guest OS in the full screen mode for macOS, Linux and Windows guest OSs. In the majority of cases, working in a guest OS with low resolution is not comfortable. Moreover, the size of that window is usually not big, and if you maximize the window’s size, the resolution of the guest OS user interface is left the same.

After installing a guest operating system (OS) on VirtualBox, the interface of the guest OS is displayed in a windowed mode by default.

Mac os on windows 10 virtualbox