edit:

i assumed the parent did not know how to do that, i tried locally and it seemed to work, but i did not pay attention to the text

original:

on the left side of the url input field you'll find "AA"(the first smaller then the seconds), tap that

then, near the bottom of the pop-up menu you'll have "Show Reader", tap that

if you're not happy with the text as displayed then, you can go back to the "AA" menu and change the options