Can VMs run on raw HW or do they neeed an OS? [closed]

I have a general question about Virtual Machines.
It is not clear to me if I need an operating system at the lower level and then install the VM and on top of that the rest or I can install a VM without any OS present.
Could someone clarify?

A VM is, by definition, an operating system running inside an operating system. So no, you can't run a VM directly on hardware.

There are always exceptions to rules, and a VM with a VHD for a disk is kind of one. Windows allows you to boot from a VHD file. But none of the settings of the VM (RAM, network configuration, other storage configuration, etc.) are used, and the guest OS inside the VHD has to support the hardware directly instead of the virtual hardware typically provided by the hypervisor.