Robot Talk is a basic Text to Speech application. It allows you to type in text, and reads it back to you in the voice of your choice (inc. your Personal Voice on iOS 17+). It uses the built-in selection of voices on your device. It also allows you the option to change the voice pitch/rate/volume. Supports both iPhone/iPad.
You can also save the output to an m4a/caf/wav/aiff audio file, which can then be shared via messaging. The app also supports Apple AirPlay, which means you can send the spoken text to an Apple AirPlay enabled speaker.