I recently did the same activity.
Yes, the procedure to upgrade a Server 2008 r2 to 2019 is to perform the upgrade to 2012 R2 first.
If the Server does not have too many configurations, but simple services, you should make the update. If, on the other hand, Server 2008R2 has numerous applications with installed services, you should create a new one and then manage the migration.
If you proceed with the 2008-> 2012-> 2019 update, check first to verify that your installed programs and services are compatible with Windows Server 2019.
- Overview about Windows Server upgrades | Microsoft Docs
- Upgrade and Conversion Options for Windows Server 2016 | Microsoft Docs
- Aggiornare Windows Server 2012 R2 a Windows Server 2019 | Microsoft Docs (in Italian but the figures help).
At the end update , remember to change the version of the operating system from "edit settings" of vm.
Thank you for your reply. I do think the best option after searching around a bit is to make e fresh install of a 2019r server and then migrate.
Now I only have to figure it out how to do it.
I turn you around these links that can be useful for the migration: