Database Export for Archive
When you need to create an archive of an Azure SQL Database, you can export the database schema and data to a BACPAC file. A BACPAC file is simply a ZIP file with an extension of .bacpac.

Considerations when exporting your database:
You must ensure that no write activity is occurring during the export.
The maximum size of a BACPAC file archived to Azure Blob storage is 200 GB.
Archiving to Azure premium storage by using a BACPAC file is not supported.
If the export operation exceeds 20 hours, it may be cancelled.

Exporting a bacpac file is not the same as backing up the database. Read Built-in Backups vs Import/Export

Self-Service Restore
Sql Database automatically creates database backups.
Backup Types: SQL Server technology is used to create full, differential, and transaction log backups.
Backup Storage: SQL Database provides up to 200% of your maximum provisioned database storage as backup storage at no additional cost.
Backup Schedule: The first full backup is scheduled immediately after a database is created. After the first full backup, all further backups are scheduled automatically and managed silently in the background. The exact timing of all database backups is determined by the SQL Database service as it balances the overall system workload.
Backup Retention: Each SQL Database backup has a retention period that is based on the service-tier of the database.