Hello,
Yes, you can first download Server 2019 evaluation version and install it. After that, you can use the product key for Server 2019 to convert the evaluation version to full version:Upgrade and conversion options for Windows Server | Microsoft Learn
There is also another option, firstly you need to optain an Server 2019 ISO image and product key for server 2019, then do an in place upgrade on this 2012r2 server:
Perform an in-place upgrade of Windows Server | Microsoft Learn
Best regards,
Molly