Thanks for this question about SDK. We are sorry about late response. Exporting a PDF to its original format like XLSX, DOCX, PPTX etc. is one of the supported capabilities of the Document Cloud Services SDK. Please have a look at the section https://www.adobe.com/devnet-docs/dcsdk_io/servicesSDK/howtos.html#export-a-pdf which explains how services SDK can be used to export a PDF back to its original format.