How to remove horizontal scrolling on mobile devices

Post paragraph font size is too small to read, I want to increase the font size of the paragraph

I added code in additional css to increase the font size after adding font size increased. but after adding code it effected with horizontal scrolling on mobile devices.

how to increase the paragraph font size without getting the horizontal scrolling issue.

the code i added to increase the font size.

p {
font-size:16px;
}
Thanks for your valuable suggestions.

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