Download operating systems as VirtualBox and VMware Images
Source: https://www.linuxvmimages.com/
Windows is a Trojan in an OS cloak, just use it for educational purposes or for experiments, don't use it as an OS at all! And Linux is much superior as a Server. IMHO also as an OS for your Desktop/Laptop.
https://developer.microsoft.com/en-us/windows/downloads/virtual-machines/
https://developer.microsoft.com/en-us/microsoft-edge/tools/vms/
Yes, you can even use Android in a VM :)
Via osboxes or linuxmimages or via this tool
https://www.genymotion.com/download/
There are more tools, but don't bother with them…
Keep in mind apple is not a fan of this
Push-button installer of macOS on VirtualBox
macos-guest-virtualbox.sh is a Bash script that creates a macOS virtual machine guest on VirtualBox with unmodified macOS installation files downloaded directly from Apple servers…
https://github.com/myspaghetti/macos-virtualbox
Looking Glass
Looking Glass is an open source application that allows the use of a KVM (Kernel-based Virtual Machine) configured for VGA PCI Pass-through without an attached physical monitor, keyboard or mouse. This is the final step required to move away from dual booting with other operating systems for legacy programs that require high performance graphics…