Common Data Services December Data Storage Improvements
File and Image Datatypes
They are both in public preview for OOB and Custom entities. Multiple File fields can be added to a single entity.
Blob storage can be used for storage of large files.
File fields can be used in CanvasApps devs immediately and will become available for Model Driven apps in the near future. https://powerapps.microsoft.com/en-us/blog/public-preview-new-file-data-type-available-via-api/
Data Storage capacity settings will play a role in the size of files that can be uploaded. https://docs.microsoft.com/en-us/power-platform/admin/capacity-storage
Use of attachments (backward compatibility)
There are no functional changes in the way Attachments for both Notes and Activities are used. All existing functionality is backwards compatible. However, we recommend that for files and images greater 5MB new File and Image datatypes be considered as the APIs are optimized for binary usage.