Content Management Systems normally support the notion of metadata. E.g., if we store a PDF attachment into a Content Management System, we are hoping that we can associate metadata to that PDF attachment in the Content Management. Examples may include Pega case id (pyID), customer name etc. Once they are set, in theory document search can be done directly within the Content Management System without the use of Pega.
Even in Azure Blob Storage, Azure allows setting of metadata. I don't think the OOTB Azure Repository allows that.
It looks like there's metadata support via the CMIS connector: