Hi,
Unfortunately Microsoft Defender for Storage does not provide real time or scheduled or on-demand scanning of files uploaded to Blob storage. It doesn't access the data in the storage account. It looks at the telemetry for anything suspicious. For example, it looks at hashes of uploaded files to see if they match ones that are known to be malicious.
The article below has more specific details:
Overview of Microsoft Defender for Storage
https://learn.microsoft.com/en-us/azure/defender-for-cloud/defender-for-storage-introduction
Please click Accept Answer if the above was useful.
Thanks.
-TP