bookish_admin-1.0.x-dev/modules/bookish_contact/bookish_contact.routing.yml

bookish_contact.success:
  path: '/contact-success'
  defaults:
    _controller: '\Drupal\sfc\Controller\ComponentController::build'
    component_id: 'bookish_contact_success'
    _title: 'Contact form submitted'
  requirements:
    _access: 'TRUE'