On IOS the browser will zoom in if the font size is less than 16px. Replace the “meta content” code with the one below to prevent the browser from zooming in. You can also change the font size to 16px to avoid zooming in the first place.
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
The meta content code should appear at the top of the theme.liquid file
Here is a screenshot of what the code should look like after you have replaced the code.