Prerequisites

The Hyper-V host and guest must both be Windows Server 2016/Windows 10 Anniversary Update or later.

VM configuration version 8.0 or greater.

An Intel processor with VT-x and EPT technology — nesting is currently Intel-only.

There are some differences with virtual networking for second-level virtual machines. See “Nested Virtual Machine Networking”.

Configure Nested Virtualization

Create a virtual machine.

While the virtual machine is in the OFF state, run the following command on the physical Hyper-V host.
This enables nested virtualization for the virtual machine.

Get-VM

copy VMName

Set-VMProcessor -VMName <VMName> -ExposeVirtualizationExtensions $true

Start the virtual machine.

Install Hyper-V within the virtual machine, just like you would for a physical server. For more information on installing Hyper-V see, Install Hyper-V.

https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/user-guide/nested-virtualization