A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
You posted in the PowerPoint section, so I'm assuming your question is about PowerPoint rather than Word. To add an audio recording to a presentation, you'll have to use PowerPoint for Windows or for Mac.
To request that a new feature be added to PowerPoint for iOS, please tap on the three-dot icon at the right end of the Ribbon. Choose Help & Feedback, then Suggest a Feature. Posting your idea allows others to vote on it. Microsoft uses this feedback to prioritize their programming.