According to this MS-Document,
You cannot directly convert an existing standard general-purpose v2 storage account. Instead, you need to create a new premium block blob storage account and then migrate your data to this new account. Additionally, use the link above as it will be helpful for creating a new Premium storage.
To copy blobs between storage accounts, you can use the latest version of the AzCopy command-line tool. Other tools such as Azure Data Factory are also available for data movement and transformation.
- The following article summarizes and points to guidance on how to move, upgrade, or migrate a storage account: Migrate a storage account
- Microsoft provides services and utilities for importing your data from on-premises storage devices or third-party cloud storage providers. Which solution you use depends on the quantity of data you're transferring. For more information, see Azure Storage migration overview.
Once all the data has been migrated to the new premium storage account, you can delete the standard storage account.The premium storage account will enhance performance when working on CAD and Revit files.
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