Change how fonts appeared

You might want to try this method from Apple Support's article:

Customize your Safari settings on iPhone – Apple Support

Eg: Change text size:

Use the Page Settings button to increase or decrease the text size.

1. Tap  on the left side of the search field.
2. Tap the large A to increase the font size or the small A to decrease it.

Accessibility options are also available:

Adjust the display and text size on iPhone – Apple Support

Eg: says:

Adjust the text size when you’re using an app

1. Open Control Center, then tap .
2. (If you don’t see , add it to Control Center—go to Settings  > Control Center, then choose Text Size).
3. Drag the slider up or down to increase or decrease the text size.

To change the text size for all apps, tap All Apps at the bottom of the screen.

Hope this helps :-)