KVM or Kernel-based Virtual Machine is a free/full virtualistation solution for Linux, it lets you turn Linux into a type 2 hypervisor (some argue its actually type 1, but it really depends on how you configure the server). KVM is not for everyone, and youwill probably be more familiar with VMware, Hyper-V or Proxmox as these all provide better management software.

Simple steps to install a free linux hypervisor

apt update
sudo apt install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils

thats the easy part, creating a virtual machine is pretty straightforwrd too, but management of multiple machines takes the word stress to a whole new level.

virt-install --name=linuxconfig-vm --vcpus=2 --memory=1024 --cdrom=ubuntu-18.04.6-desktop-amd64.iso --disk size=50 --os-variant=ubuntu1804

How to remotely manage a linux hypervisor

An application called Virt-Manager is pretty useful for managing VM’s both locally and remotely, and can be installed easily enough:

apt update
apt install virt-manager
apt install ssh-askpass-gnome

be aware that virtual machine manager is very buggy, but it makes the creation of virtual machines much simpler and eases the pain of managing a small number of machines.