Is it possible to attach other documents such as PDF and Word documents not needing signatures to the email with the DocuSign document?

Yes, you can either add an additional document during the envelope creation or if you need a Recipient to add a document you can add an "Attachment" tag assigned to that Recipient. During envelope creation you just upload another document. If using the "attachment" tag you add it to a location and either set that attachment tag as Required or Optional.

Here is a DocuSign article on adding an attachment tag

https://support.docusign.com/en/guides/signer-guide-signing-adding-attachments-new