Related posts only by tags

function king_tags_only_related_posts( $related_args ) {

    $post_tags = get_the_terms( $post->ID, 'post_tag' );
    $tags = wp_list_pluck( $post_tags, 'slug' );

    $related_args['tax_query'][] = array(
        'taxonomy' => 'post_tag',
        'field'    => 'slug',
        'terms'    => $tags,
    );

    return $related_args;
}

add_filter('kadence_related_posts_args', 'king_tags_only_related_posts');