In what kind of service does a seated hostess or host place food from bowls and amp platters on guests' plates?

The service you’re referring to is known as "plated service" or "plate service." In this style, a seated hostess or host portions food from bowls and platters onto guests' plates, ensuring that each guest's meal is served individually. This method allows for a more formal dining experience and can enhance presentation, as each dish is carefully arranged before being presented to the guest.