How to Automatically Create Post Tags from Post Title

Here is a simple WordPress plugin that will automatically add tags from the post title when saving posts.

<?php
/**
 * Plugin Name: Auto Tag
 * Description: Automatically creates tags from the post title and assigns them to the post.
 * Version: 1.0
 * Author: Stefan Pejcic
 */

function auto_tag_from_title($post_id) {
  $post_title = get_the_title($post_id);
  $tags = explode(" ", $post_title);

  wp_set_post_tags($post_id, $tags, true);
}
add_action('save_post', 'auto_tag_from_title');

To use this plugin, simply copy and paste the code into a new file and save it as auto-tag.php in the wp-content/plugins directory of your WordPress site. Then, go to the Plugins page in the WordPress admin dashboard and activate the plugin. Every time a post is saved, the plugin will automatically create tags from the post title and assign them to the post.