Exclude pages that have been noindex-ed in Rank Math from WP search

functions.php

<?php // Do not copy this line

function child_exclude_noindex_from_search( $query ) {

	if( $query->is_main_query() && $query->is_search() ) {

		$meta_query = isset( $query->meta_query ) ? $query->meta_query : array();
		$meta_query['noindex'] = array(
			'key' => 'rank_math_robots',
			'value' => "noindex",
			'compare' => 'NOT EXISTS',
		);

		$query->set( 'meta_query', $meta_query );
	}
}
add_action( 'pre_get_posts', 'child_exclude_noindex_from_search' );