Docker upgrade question

There are volumes created by the pwd.yml, I think I don’t need to create the volumes by myself.

I am referring this thread
Docker ERPNext update

I am new to ERPNext, I guess there is a default site create by the pwd.yml. But what is the name of the site?

Back to my original question, is that I need to run the following command everytime I pull a new image?

docker-compose exec backend bench migrate