The only user accessible field in Pages v5.6.1 is the Preferences : General : Author field. On export to Word, or Pages '09 format, this Author field does not get applied to the exported document. I checked this in Pages '09 document inspector (info), Bean's (.docx) tags, and LibreOffice Properties — all showing blank info fields.
Otherwise, Pages v5.6.1 document internal files are encrypted, and attempts to look at these will be met with gibberish.
Understand that Pages v5.6.1 is very far from a Word clone, (and functional word processor) and does not open or edit Word documents in their native document format. You cannot open a Word document and then just save it. You must open it, and save as another document name. Not all functionality in Word 2010/2013 is supported by Pages v5.6.1 and a .docx journey through Pages v5.6.1 may not leave it in the same state as when it was created in MS Word.