smsplatform-1.0.x-dev/modules/smsplatform_devel/smsplatform_devel.routing.yml

smsplatform_devel.message:
  path: '/admin/config/development/sms'
  defaults:
    _title: 'Test SMS'
    _form: '\Drupal\smsplatform_devel\Form\SmsDevelMessageForm'
  requirements:
    _permission: 'smsplatform_devel form'