/* Query Filter for Posts Pages and Search Pages */
function query_filter_for_posts_search_pages( $query ) {
	if ( is_front_page() || $query->is_search() ) {
		$query->set( 'orderby', 'modified' );
		$query->set( 'order', 'DESC' );
	}
}
add_action( 'pre_get_posts', 'query_filter_for_posts_search_pages' );