Case Project $5-4$ Moving to Windows Server $2019$

The IT department has already been testing Windows Server $2019,$ and some time ago purchased licenses to convert its Windows Server $2012$ R$2$ Standard Edition servers to Windows Server $2019$ Standard Edition. Two of the servers are running the Server Core installation of Windows Server $2012$ R$2.$ Management wants all servers to run Windows Server $2019$ with a GUI installation. In addition, a new high$-$performance server has been purchased with the intent of making it a virtualization server. Management wants to reduce the number of physical servers from $28$ to $20.$ Explain the general process the department must follow to convert to Windows Server $2019$ and reduce the number of physical servers.