Immersive Reader in Edge lets users pick the voice in which pages are read aloud, lets users chose the speed at which pages are read aloud, and it lets users adjust the size and spacing of the font that is displayed while pages are read aloud. There are some additional features that are also helpful in some situations. For example, you can have parts of speech highlighted by Edge. In this short video I provide a demonstration of using Immersive Reader in Microsoft Edge.
Here are a few more ways to use Immersive Reader.
How to Highlight, Annotate, and Share Pages in Microsoft Edge
How to Have PDFs Read Aloud by Using Microsoft Edge
How to Use Immersive Reader in Microsoft Forms