Grant is correct. You're trying to think about this incorrectly, according to what MS has built.
Azure SQL DB <> SQL Server database on premise
In fact, the version of Azure SQL DB is often greater than SQL Server db on premise because they deploy changes there first, so it's like perpetually v.Next and not a version that matches 2016, 2017, etc.
Even in Azure, I can't restore a backup of Azure SQL DB over an existing db. The paradigm has changed. If you're testing things and looking to move to Azure SQL DB from on premises, you're going to be constantly migrating to new dbs, not restoring/refreshing old ones.