While reading a book:

Contrast: Tap screen to show toolbar, and move Contrast Slider to ajust contrast.

Font Size: Tap screen to show toolbar, tap Font Size icon to enlarge or shrink font size.

Font Family: Tap screen to show toolbar, tap icon 'More..' to open App Settings, tap Article Text Font to change font style.

Turning or Scrolling Page: Tap screen to show toolbar, tap icon 'More..' to show Action Sheet, tap Allow Page Scrolling to scroll page. (show me)

Page Turning Speed: Tap screen to show toolbar, tap icon 'More..' to open App Settings, tap Page Turning Style to change.

Dark or light Mode: Swipe from top-right corner of screen to show Control Center. Tap dark mode icon to switch between dark/light mode. (show me)