@andSmv thanks for coming back on this. Actually you are right it is a limit on Windows OS as per documentation here https://learn.microsoft.com/en-us/windows-server/get-started/editions-comparison-windows-server-2019?tabs=full-comparison. Should have checked this before I asked the question

Hi Guys, any of you got lock to configure more than 64 CPUs for Windows OS VM? if I set apci to 0 then vm would no longer boot