I got this PowerShell a long time ago, it is still working in CloudShell...
$myregion = "westeurope"
Get-AzureRmVMSize -Location $myregion | Where-Object { $.NumberOfCores -gt 16 } | Where-Object {$.MemoryInMB -gt 32000} | Out-GridView
If you have a list of regions, you might build an outer loop to step through that list...