Here's how to magnify the text within a title on Epic from different devices:
iOS & Android: While you are reading a book, simply use the pinch gesture to zoom in and out.
Epic Website: Open the book, and then use the + and - buttons on the right side to zoom in and out. (After you are zoomed in, you can drag the page around by holding down the left mouse button and dragging the mouse.)
To turn the pages while zoomed in, click the arrow on the right side or the arrow on the left to go back a page.