StandardHooks.php

<?php

namespace Drupal\standard\Hook;

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

/**
 * Hook implementations for standard.
 */
class StandardHooks {
    
    /**
     * Implements hook_form_FORM_ID_alter() for install_configure_form().
     *
     * Allows the profile to alter the site configuration form.
     */
    public function formInstallConfigureFormAlter(&$form, FormStateInterface $form_state) : void {
        $form['#submit'][] = [
            $this,
            'installConfigureSubmit',
        ];
    }
    
    /**
     * Submission handler to sync the contact.form.feedback recipient.
     *
     * @param array $form
     *   Form array.
     * @param \Drupal\Core\Form\FormStateInterface $form_state
     *   The current form state.
     */
    public function installConfigureSubmit(array $form, FormStateInterface $form_state) : void {
        $site_mail = $form_state->getValue('site_mail');
        ContactForm::load('feedback')->setRecipients([
            $site_mail,
        ])
            ->trustData()
            ->save();
    }

}