Note: The maximum allowed document size is 100 MB. In order to send a document from within WhatsApp, the document must be saved locally on your phone. Alternatively, WhatsApp will appear as an option in the share menu of apps that handle documents like Dropbox and Google Drive. When you download a document, it will be automatically saved in your WhatsApp Documents folder:
WhatsApp/Media/WhatsApp Documents, which can be accessed with a file explorer app.
To forward media, documents, locations or contacts from one conversation to another:
When you forward media, documents, locations or contacts, you don't have to upload it again, and therefore it will send faster and use less data. Any forwarded messages that weren't originally sent by you will be displayed with the "Forwarded" label.
Note: Captions won't be forwarded along with media.
Learn how to send media, documents, location or contacts on: iPhone