Overwriting Page–type is not working

Hello guys, recently i’m working with Drupal 8 to develop my page.
But then i struggle on how to overwrite the page–(type).

I’ve been doing it with Drupal 7 and it works just easy just by creating a file that named page–(type).tpl.php
BUt then in drupal 8 i follow this (https://www.drupal.org/node/2521876) and it still not working.

Can somebody help me? i’ve been searching for almost a week, and trying to do what other ppl do, but i cant seems to overwrite it.
Is this feature (somehow) need more configuration?

What currently i had done :

1. on my_theme.theme, i put this code in the most bottom of the file

/**
 * Implements hook_theme_suggestions_HOOK_alter().
 */
function onlinepajak_theme_suggestions_page_alter(array &$suggestions, array $variables) {

  if ($node = Drupal::routeMatch()->getParameter('node')) {
    $content_type = $node->bundle();
    $suggestions[] = 'page__'.$content_type;
  }
}

2. i create a file named page–blog_page.html.twig || page–blog-page.html.twig || page–blogpage.html.twig
and my machine name for that content type is blog_page.

It stressed me out , because this is the only way i can differ my content types styling and structure. (as far as i know, if there’s another way, i might want to know it 🙂 )

Thank you before. !

Drupal version: 


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