This article explains how to use Live Speech and how to turn it on. Live Speech is an accessibility feature of the iPhone, iPad, and Mac that allows users with speech impairments or who cannot speak to type messages and then have them spoken aloud. This makes it easier for these users to make and receive phone calls and FaceTime calls.
How to set up and use Personal Voice and Live Speech on iPhone and iPad | Apple Support
To use Live Speech to type messages that will be read aloud, follow these steps:
Triple-click the side button on your iPhone or the top button on your iPad.
When the Live Speech text input field appears, type your message using the keyboard.
