Automatically Add a “Featured” Label to Sticky WordPress Posts

/**
 * Add a "Featured" label to sticky blog posts
 */
function custom_add_sticky_featured_label( $title, $post_id ) {

    if ( is_admin() || get_post_type( $post_id ) !== 'post' ) {
        return $title;
    }

    if ( is_sticky( $post_id ) ) {
        $title .= ' <span class="featured-post-label">Featured</span>';
    }

    return $title;
}

add_filter( 'the_title', 'custom_add_sticky_featured_label', 10, 2 );