Maximum number of virtual CPUs configurable in a Windows and Linux virtual machine - achievable numbers vary greatly with specific guest OS version, please check! (240 vCPUs supported for e.g.: Windows Server 2012, 2008R2, CentOS 5.7. 5.8, 6.0-6.3, RHEL 6-6.3, SLES11SP2 etc.).
For all supported guests with Server 2016 see https://technet.microsoft.com/en-us/windows-server-docs/compute/hyper-v/supported-windows-guest-operating-systems-for-hyper-v-on-windows