You can use this shortcut with share sheet, as a widget or directly from the Shortcuts app.
Demonstration Video on Vimeo: Read with Speed
Simply highlight some text (e.g. from Notes, your favourite news, a script or whatever…), open share sheet and choose Read with Speed. When starting the shortcut directly from within the Shortcuts app or the Today View, your clipboard content will be automatically loaded into Read with Speed.
After the shortcut opens a new window, where you can start speed reading. Simply tap the READ button to start. Hit it again to PAUSE reading. A slider is used to give you the possibility to change the reading position.
The default Words Per Minute (WPM) is 200, but you can adjust it as you like with a slider. The shortcut will remember these settings. That said, even if you quit the Shortcuts App your WPM settings will remain if you use Read with Speed again.
By default words with less than four characters will merge and display together to improve the reading speed.
The whole design is responsive and will display great starting with iPhone 5/SE.
The default font size is 32px, but you can change this to your needs with a dedicated slider. This setting will be saved as well, so you don’t need to change it each time you use the shortcut.
There’s even a Dark Mode toggle, if you like it white on black!
NOTE: I found this on the Internet, it's created by @ROP not me.
Siri is supported
ShareSheet is supported
Widget is supported