Before discussing this question it is important to understand what exactly Project Scope is.
Although certain artifacts and deliverables might not be delivered to the customer, they are still a part of the Project Scope and thus the Project Management Plan (and any other designated artifact for that matter) is indeed a part of the Project Scope
SCOPE MANAGEMENT PLAYLIST
SCOPE MANAGEMENT FAQs
PROJECT MANAGEMENT PLAN PLAYLIST
SHOP FOR PMP AT AMAZON INDIA