I have a Azure SQL Db configure with DTU-based pricing model. I'm trying to create a Replica in a secondary region for the DB. But when I try to configure it using the Azure portal, there is no option to select the service tier as DTU. Is this a limitation or am I missing some configuration?
Based on the screen you shared with us it seems to me you are not following the steps outlined on Microsoft Documentation.
If I follow the steps provided on the documentation, I initiate the creation of the replica by selecting the options shown on below screenshot:
When I do that Azure Portal shows me a different web page to continue the process of creating the replica than the one you shared with us.
If I scroll down that page, I am able to see the service tier. Basic tier (DTU model) in my case.