How to generate sub assets in DAM ?

Out of the box from CQ 5.4 onwards, sub-assets generation is disabled. Based on your use case if you have a requirement to automatically generates a sub-asset for each page in the file  the steps are

• Add the "Create Sub assets" step to the DAM update asset workflow from the sidekick. (Attaching the screenshot for a reference)
• Save the changes.
• Any new uploads will now have the pages listed in subassets.

Note:

• For any additional use case need to write a custom workflow step.  
• This process can add load to your server during asset upload especially if you have documents with many pages.