Hi Yonghu shi •,
Welcome to Microsoft Q&A forum and thanks for using Azure Services.
As I understand, you are unable to find option of SQL Data Sync for your Azure SQL Database.
Thanks for the screenshot, I could see that the Pricing tier is Hyperscale.
As general limitation of SQL Data Sync:
Using an Azure SQL Hyperscale database as a Hub or Sync Metadata database isn't supported. However, a Hyperscale database can be a member database in a Data Sync topology.
Please try with a different tier and sync. Let us know if you have further queries.