You can add this code on either the Custom CSS or a child theme style.css
You can use either of the two code samples:
This adds padding to the content only. I’m guessing this is what you’re after.
.single-view .entry-content {
padding: 0 20px;
}
This adds padding to the content including the title on top and the comments underneath.
.single #content, .page #content {
padding: 0 20px;
}
Modify the numbers to suit your needs.
0 represents top and bottom padding.
20px represents the left and right padding.