Convert the attachments to files with the new Attachments to Files app from Salesforce Labs.

AppExchange Link – https://appexchange.salesforce.com/appxListingDetail?listingId=a0N3A00000EHAmyUAH

You can use the Attachments to Files tool to run bulk jobs that convert large numbers of attachments. Attachments are organized by the object they’re associated to. After the conversion, you can delete the attachments from the org to free up space.