Custom page template for content pages
You are looking for hook_theme_suggestions_HOOK_alter().

HOOK is the name of the template, in your case, page. You should be able to add the following to your theme in the .theme file.

In there, do something like this:

function yourtheme_theme_suggestions_page_alter(array &amp;$suggestions, array $variables) {
  if ($node = \Drupal::routeMatch()-&gt;getParameter('node')) {
    $suggestions[] = 'page__node__' . $node-&gt;getType();
  }
}