I built a WordPress (Google Click to Deploy) environment using GCP 's Cloud Launcher.
Is it possible to use .appspot.com domain like GAE in this environment
If so, what procedure should we implement?
Thank you.
I'm afraid it is not possible since .appspot.com is only for GAE.
You can do it using Cloud DNS and any registrar for your custom domain.
Here you have a quick-start related with this topic. [Cloud DNS doc]