opencase/modules/opencase_defaults/opencase_defaults.module

<?php

/**
 * @file
 * Contains opencase_defaults.module.
 */

use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\user\Entity\Role;
use Drupal\user\RoleInterface;

/**
 * Implements hook_help().
 */
function opencase_defaults_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    // Main module help for the opencase_defaults module.
    case 'help.page.opencase_defaults':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('OpenCase Default Configuration') . '</p>';
      return $output;

    default:
  }
}

/**
 * Implements hook_preprocess_page_title
 *  
 * Modify the page title to include more information 
 */
function opencase_defaults_preprocess_page_title(&$variables) {
  
   $route_name = \Drupal::routeMatch()->getRouteName();
    switch ($route_name) {
      case 'entity.oc_case.canonical':
        $case = \Drupal::routeMatch()->getParameter('oc_case');
        $variables['title'] = $case->getName() . ": Case Details and Files";
        break;
      case 'view.cases.page_1':
        $actor_id = \Drupal::routeMatch()->getParameter('actor_id');
        $actor = \Drupal::entityTypeManager()->getStorage('oc_actor')->load($actor_id); 
        $variables['title'] = $actor->getName() . ": Cases";
        break;
      case 'view.activities.page_1':
        $case_id = \Drupal::routeMatch()->getParameter('case_id');
        $case = \Drupal::entityTypeManager()->getStorage('oc_case')->load($case_id); 
        $variables['title'] = $case->getName() . ": Activities";
        break;
    }
}
/**
 * Implements hook_theme().
 */
function opencase_defaults_theme() {
  return [
    'opencase_defaults' => [
      'render element' => 'children',
    ],
  ];
}