How to sort by WordPress custom field for number of characters?

Question

PHP

I use a WP plugin to count and display the number of characters of posts https://wordpress.org/plugins/posts-character-coun...
Here is the php file

<?php

class Posts_Character_Count_Admin {
  public static function init() {
    $plugin = new self();
    add_action( 'admin_init', array( $plugin, 'admin_init' ) );
  }

  public function admin_init() {
    // Only run our customization on the 'edit.php' page in the admin
    add_action( 'load-edit.php', array( $this, 'admin_edit_screens' ) );

    // Only run our customization on the 'post.php' page in the admin
    add_action( 'load-post.php', array( $this, 'admin_post_screens' ) );
  }

  // Добавить сортировку по количеству знаков в столбце, чтобы всем управлять должностей экранов в том числе страниц
  public function admin_edit_screens() {
    // Add the character count column to all manage posts screens except pages
    add_filter( 'manage_posts_columns', array( $this, 'admin_edit_columns' ) );
    add_action( 'manage_posts_custom_column', array( $this, 'admin_edit_column_values' ), 10, 2 );

    // Add the character count column to the manage pages screen
    add_filter( 'manage_pages_columns', array( $this, 'admin_edit_columns' ) );
    add_action( 'manage_pages_custom_column', array( $this, 'admin_edit_column_values' ), 10, 2 );
  }

  // Add the character count to the edit screens of all post types including pages
  public function admin_post_screens() {
    add_action( 'admin_footer', array( $this, 'post_edit_screen_admin_footer' ) );
  }

  /* Methods and Filters for the column in the Manage Posts/Pages SubPanel */

  public function admin_edit_columns( $columns ) {
    $columns['count'] = __( 'Character Count', 'posts-character-count-admin' );

    return $columns;
  }

  public function admin_edit_column_values( $column, $post_id ) {
    global $post;
    if ( 'count' == $column ) {
      $stat = new Posts_Character_Count( $post->post_content );
      echo $stat->count_characters() . ' ' . __( '', 'posts-character-count-admin' );
    }
  }

  /* Methods and Action for the characters count in the Edit Posts/Pages SubPanel */

  public function post_edit_screen_admin_footer() {
    global $post;

    if ( ! empty( $post ) && isset( $post->post_content ) ) {
      $stat = new Posts_Character_Count( $post->post_content );

      $template = __(
          'Character count:',
          'posts-character-count-admin'
        ) . ' %d ' . __(
          'characters (incl. spaces)',
          'posts-character-count-admin'
        );

      printf(
        '<script type="text/javascript">
          jQuery(document).ready(function ($) {
            var $div = $("#post-status-info");
            if ($div.length > 0) {
              $div.append("<span class=\"inside\" style=\"margin-left: 10px;\">%s</span>");
            }
          });
        </script>', sprintf( $template, $stat->count_characters() )
      );
    }
  }
} // End class

Accordingly, it is necessary to add to the function to create a sort

add_filter('manage_edit-post_sortable_columns', 'add_count_sortable_column');
function add_count_sortable_column($sortable_columns){
  $sortable_columns['count'] = 'count_count'; //пробовал здесь просто date, опустив след. пункт, все равно сортирует рандомно..
  return $sortable_columns;
}

add_filter('pre_get_posts', 'add_column_count_request');
function add_column_count_request( $object ){
  if( $object->get('orderby') != 'count_count' )
    return;
    
  $object->set('meta_key', '<b>ЧТО ТУТ НУЖНО ПОСТАВИТЬ</b>');
  $object->set('orderby', 'meta_value_num');
}

WHAT SHOULD I PUT HERE - what should I put here?
I removed the text in the plugin so that it just displays numbers, so you can use meta_value_num
And if you still use not only numeric fields, then use meta_value instead of meta_value_num?