Add Boostrap CDN

I'm new to drupal 9... I find out that the head of my drupal page is in the html.html.twig file. I wanna add the boostrap CDN in to the head of my file, but when i attached it, nothing shows up. The script is not even showed in the source page. I think the entire head of the document is not visualized. How can I do?

{# /**
 * @file
 * Default theme implementation for the basic structure of a single Drupal page.
 *
 * Variables:
 * - logged_in: A flag indicating if user is logged in.
 * - root_path: The root path of the current page (e.g., node, admin, user).
 * - node_type: The content type for the current node, if the page is a node.
 * - head_title: List of text elements that make up the head_title variable.
 *   May contain one or more of the following:
 *   - title: The title of the page.
 *   - name: The name of the site.
 *   - slogan: The slogan of the site.
 * - page_top: Initial rendered markup. This should be printed before 'page'.
 * - page: The rendered page markup.
 * - page_bottom: Closing rendered markup. This variable should be printed after
 *   'page'.
 * - db_offline: A flag indicating if the database is offline.
 * - placeholder_token: The token for generating head, css, js and js-bottom
 *   placeholders.
 *
 * @see template_preprocess_html()
 *
 * @ingroup themeable
 */
#}
<!DOCTYPE html>
<html{{ html_attributes }}>
  <head>
  {% block stylesheets %}
    <link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet">
    {% endblock %}
    {% block javascripts %}
    <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.bundle.min.js"></script>
    {% endblock %}
    <head-placeholder token="{{ placeholder_token }}">
    <title>{{ head_title|safe_join(' | ') }}</title>
    <css-placeholder token="{{ placeholder_token }}">
    <js-placeholder token="{{ placeholder_token }}">
    </head>
  <body{{ attributes }}>
    {#
      Keyboard navigation/accessibility link to main content section in
      page.html.twig.
    #}
    <a href="#main-content" class="visually-hidden focusable">
      {{ 'Skip to main content'|t }}
    </a>
    {{ page_top }}
    {{ page }}
    {{ page_bottom }}
    <js-bottom-placeholder token="{{ placeholder_token }}">
  </body>
</html>
#}

Solution

I resolved the problem. There was another html.html.twig file that was overriding the otherone. If you find the right file u can simple add <link type="text/css" href="myPathForCssFile.css"/>