Using Pagination Library

Hi all, I want to use the default pagination library coming with CI4 for paginating posts in a page. So, I created the following controller. The result of a query builder is stored in the protected variables $posts. In the index page I have inserted the corresponding code for links creation (<?= $pager->links() ?>). Regardless the number of posts in the page, the pager always creates one link (page). See image below. How I can tell to the pager to create more links (pages)? FYI. I have set $perPage public variable equal to 3 in app/Config/Pager.php.

PHP Code:

<?php

namespace App\Controllers;

class Blog extends BaseController
{
    protected $posts;

    public function __construct()
    {
        $db = db_connect();
        $query_posts = $db->query("SELECT * FROM posts ORDER BY created_at DESC");
        $this->posts = $query_posts->getResult();
    }

 public function index()
 {
     $data = array(
          'posts'        => $this->posts,
          'pager'        => \Config\Services::pager()
     );

     return view('blog', $data);
    }
}