$block = module_invoke('block', 'block_view', '4');
$text_block = render($block['content']);

$bid = ??? // Get the block id through config, SQL or some other means
$block = Drupalblock_contentEntityBlockContent::load($bid);
$render = Drupal::entityTypeManager()->
  getViewBuilder('block_content')->view($block);
return $render;

$block_manager = Drupal::service('plugin.manager.block');
// You can hard code configuration or you load from settings.
$config = [];
$plugin_block = $block_manager->createInstance('system_breadcrumb_block', $config);
// Some blocks might implement access check.
$access_result = $block_plugin->access(Drupal::currentUser());
// Return empty render array if user doesn't have access.
if ($access_result->isForbidden()) {
  // You might need to add some cache tags/contexts.
  return [];
}
$render = $plugin_block->build();
// In some cases, you need to add the cache tags/context depending on
// the block implemention. As it's possible to add the cache tags and
// contexts in the render method and in ::getCacheTags and
// ::getCacheContexts methods.
return $render;

$block = DrupalblockEntityBlock::load('config.id');
$render = Drupal::entityTypeManager()
  ->getViewBuilder('block')
  ->view($block);
return $render;

$block = DrupalblockEntityBlock::load('my_block_id');
$variables['My_region'] = Drupal::entityManager()
          ->getViewBuilder('block')
          ->view($block);

{% if page.My_region %}
    {{ page.My_region }}
{% endif %}

public function content() {
    $block = DrupalblockEntityBlock::load('my_block_id');
    $block_content = Drupal::entityManager()
      ->getViewBuilder('block')
      ->view($block);

          return array(
        '#type' => 'container',
        '#attributes' => array(
          'class' => array("Myclass"),
        ),
        "element-content" => $block_content,
        '#weight' => 0,
      );
}

$con = DrupalblockBlockViewBuilder::lazyBuilder('bartik_search', 'full');
$d = Drupal::service('renderer')->renderPlain($con);
print $d->__toString();

// You need a block_id! to get it just click configure in the desire block and you'll get url like this /admin/structure/block/manage/bartik_search   the last part of the parameter is the block id
$block = DrupalblockEntityBlock::load('bartik_search');
$block_content = Drupal::entityManager()
  ->getViewBuilder('block')
  ->view($block);

return array('#markup' => drupal_render($block_content));

$view = views_embed_view('my_view_name', 'my_display_name');

return [
  ['description' => [
    '#theme' => 'your_theme_hook',
    '#your_variable => $view
  ]
]

function hook_theme($existing, $type, $theme, $path) {
  return array(
    'your_theme_hook' => array(
      'variables' => [
        'your_variable' => NULL,
      ]
    )
  )
}

{{ your_variable }}

return array('#markup' => drupal_render($block_content));

$block = DrupalblockEntityBlock::load ('my_bock_id');
$block_content = Drupal::entityManager ()->
  getViewBuilder ('block')->
  view ($block);

return array (
    '#type' => 'container',
    'element-content' => $block_content
);

return ['#markup' => Drupal::service ('renderer')->render ($block_content)];