drupal/core/modules/user/user.routing.yml

user_register:
  pattern: '/user/register'
  defaults:
    _content: '\Drupal\user\UserRouteController::register'
  requirements:
    _access_user_register: 'TRUE'

user_autocomplete:
  pattern: '/user/autocomplete'
  defaults:
    _controller: '\Drupal\user\UserAutocompleteController::autocompleteUser'
  requirements:
    _permission: 'access user profiles'

user_autocomplete_anonymous:
  pattern: '/user/autocomplete/anonymous'
  defaults:
    _controller: '\Drupal\user\UserAutocompleteController::autocompleteUserAnonymous'
  requirements:
    _permission: 'access user profiles'

user_account_settings:
  pattern: '/admin/config/people/accounts'
  defaults:
    _form: '\Drupal\user\AccountSettingsForm'
  requirements:
    _permission: 'administer users'