Can PhpStorm autocomplete methods in Drupal::service?
The auto-complete suggestions are based on the type of return value documented in the \Drupal::service() doxygen comment. Since the method may return service of any kind the type of return value is mixed.

That means auto-complete is not possible unless you explicitly specify type of the service.

/** @var \Drupal\Core\Config\ConfigFactoryInterface $config_factory */
$config_factory = \Drupal::service('config.factory');


For some particular services you can use dedicated  methods like \Drupal::configFactory() or \Drupal::config() which have properly documented return value.

Notice that generally dependency injection is more preferable method for accessing services.