There is nothing on this forum which controls your Apple iPhone “Reader Mode”
It is a feature that is in Safari browser which Apple believes improves your reading of the site better. A simple google search will tell you all about it and how to disable it.
Here’s how to turn Reader mode off for all Safari pages:
Open the Settings app.
Scroll down and tap on Safari.
Scroll all the way down and tap on Reader.
Tap the green All Websites toggle to turn it off. The toggle will turn gray.