Chrome OS 79 is expected to add custom settings to the Reader Mode on Chromebooks, including choice of font, font size and more. Here’s a great example of what it should like, based on a currently available Chrome extension.
Distill Page
Chrome Reader Mode getting an icon to toggle web page views
When Chrome OS 75 arrives on your Chromebook, you’ll finally have a “reader mode” option for distraction-free browsing. Currently, enabling this mode requires a trip to the Chrome menu; a new icon switch is in the works for faster mode switches.
