How to theme all pages after a certain url I'm using Drupal 8.7.8 

I would like to create a new twig theme file for all pages that are after a certain URL. 
For example: example.com/example/this-page

"This-page" is what I want to create my twig file for. But there doesn't seem to be an option in the theme debugging for anything after example.com/example. 

Another example...The twig file would be named page--example.html.twig ... Is there no way to say page--example/*.html.twig ?
You can use THEME_NAME_theme_suggestions_page_alter to create your own template suggestions!

In your theme:

File: my_theme/my_theme.theme

/**
 * Implements hook_theme_suggestions_HOOK_alter.
 */
function my_theme_suggestions_page_alter(&amp;$suggestions, $variables) {
  $current_path = \Drupal::service('path.current')-&gt;getPath();
  $current_path = \Drupal::service('path.alias_manager')-&gt;getAliasByPath($current_path);

  if (strpos($current_path, 'this-page') !== false) {
    $suggestions[] = 'page__this_page';
  }
}


File: my_theme/templates/page--this-page.html.twig

// Output html and stuff


Obviously replace "my_theme" with the name of your custom theme.

Here is a nice tutorial that expands more on it.