The Exchange 2019 Sizing Calculator was released a few weeks ago.

https://techcommunity.microsoft.com/t5/Exchange-Team-Blog/Announcing-The-Exchange-Server-2019-Sizing-Calculator/ba-p/644180

The calculator is now optimized for Exchange 2019 and has the following updates:

  • Improved Virtualisation Support
  • Updated SPECint Benchmark
  • Support for MetaCache (new feature in Exchange 2019)
  • Now has a hard 2TB mailbox database limit

See the link for further details.