drupal/core/profiles/demo_umami/demo_umami.profile

<?php

/**
 * @file
 * Enables modules and site configuration for a demo_umami site installation.
 */

use Drupal\contact\Entity\ContactForm;
use Drupal\Core\Form\FormStateInterface;

/**
 * Implements hook_form_FORM_ID_alter() for install_configure_form().
 *
 * Allows the profile to alter the site configuration form.
 */
function demo_umami_form_install_configure_form_alter(&$form, FormStateInterface $form_state) {
  $form['site_information']['site_name']['#default_value'] = 'Umami Food Magazine';
  $form['#submit'][] = 'demo_umami_form_install_configure_submit';
}

/**
 * Submission handler to sync the contact.form.feedback recipient.
 */
function demo_umami_form_install_configure_submit($form, FormStateInterface $form_state) {
  $site_mail = $form_state->getValue('site_mail');
  ContactForm::load('feedback')->setRecipients([$site_mail])->trustData()->save();

  $password = $form_state->getValue('account')['pass'];
  demo_umami_set_users_passwords($password);
}

/**
 * Sets the password of admin to be the password for all users.
 */
function demo_umami_set_users_passwords($admin_password) {
  // Collect the IDs of all users with roles editor or author.
  $ids = \Drupal::entityQuery('user')
    ->accessCheck(FALSE)
    ->condition('roles', ['author', 'editor'], 'IN')
    ->execute();

  $users = \Drupal::entityTypeManager()->getStorage('user')->loadMultiple($ids);

  foreach ($users as $user) {
    $user->setPassword($admin_password);
    $user->save();
  }
}

/**
 * Implements hook_toolbar().
 */
function demo_umami_toolbar() {
  // Add a warning about using an experimental profile.
  // @todo This can be removed once a generic warning for experimental profiles
  //   has been introduced. https://www.drupal.org/project/drupal/issues/2934374
  $items['experimental-profile-warning'] = [
    '#weight' => 999,
    '#cache' => [
      'contexts' => ['route'],
    ],
  ];

  // Show warning only on administration pages.
  $admin_context = \Drupal::service('router.admin_context');
  if ($admin_context->isAdminRoute()) {
    $items['experimental-profile-warning']['#type'] = 'toolbar_item';
    $items['experimental-profile-warning']['tab'] = [
      '#type' => 'inline_template',
      '#template' => '<a class="toolbar-warning" href="{{ more_info_link }}">This site is intended for demonstration purposes.</a>',
      '#context' => [
        'more_info_link' => 'https://www.drupal.org/node/2941833',
      ],
      '#attached' => [
        'library' => ['demo_umami/toolbar-warning'],
      ],
    ];
  }
  return $items;
}