Modify the meta viewport setting in the Divi theme

functions.php

<?php
// Source: https://divi.help/threads/the-user-scalable-no-attribute-is-used-in-the-meta-name-viewport-element-or-the-maximum-sc.10458/

/**
 * Remove the default viewport meta from Divi.
 */
function db_remove_et_viewport_meta() {
	remove_action( 'wp_head', 'et_add_viewport_meta' );
}
add_action( 'after_setup_theme', 'db_remove_et_viewport_meta' );

/**
 * Add new viewport meta line to head.
 */
function db_enable_pinch_zoom() {
	echo '<meta name="viewport" content="width=device-width, user-scalable=yes, initial-scale=1.0, minimum-scale=0.1, maximum-scale=10.0">';
}
add_action( 'wp_head', 'db_enable_pinch_zoom' );