WordPress at a glance
function is not described

_ipad_meta() WP 3.3.0

No Hooks.

Return

Nothing (null).

Usage

_ipad_meta();

Code of ipad meta: wp-admin/includes/misc.php WP 5.2.2

<?php
function _ipad_meta() {
	if ( wp_is_mobile() ) {
		?>
		<meta name="viewport" id="viewport-meta" content="width=device-width, initial-scale=1">
		<?php
	}
}