How do I set the tab title?
If you use Meta tag module, you can use following method. From this method you can get Meta tag title and other Meta tags for view section also.

my_module.services.yml

services:
my_module.route_subscriber:
class: Drupal\my_module\Routing\RouteSubscriber
tags:
  - { name: event_subscriber }


my_module/src/Routing/RouteSubscriber.php

namespace Drupal\my_module\Routing;

use Drupal\Core\Routing\RouteSubscriberBase;
use Symfony\Component\Routing\RouteCollection;

/**
 * Listens to the dynamic route events.
 */
class RouteSubscriber extends RouteSubscriberBase {

    /**
     * {@inheritdoc}
     */
    protected function alterRoutes(RouteCollection $collection) {

        if ($route = $collection-&gt;get('entity.node.canonical')) {
            $route-&gt;setDefaults(array(
                '_controller' =&gt; 'Drupal\my_module\Controller\MymoduleController::view',
            ));
        }
    }
}


MymoduleController.php

namespace Drupal\my_module\Controller;

use Drupal\Core\Entity\EntityInterface;
use Drupal\node\Entity\Node;
use Drupal\node\Controller\NodeViewController;

class MymoduleController extends NodeViewController {

    public function view(EntityInterface $node, $view_mode = 'full', 
    $langcode = NULL) {

        $elements = getRequiredDetails($node);

        return [
            '#theme'    =&gt; 'your-theme',
            '#contents' =&gt; $elements,
            '#attached' =&gt; [
                'library'=&gt; [
                    'my_content/my_content',
                ],
            ],
        ];
    }
}