During the 'Maintain' step of the 'business case management' technique in PRINCE2, the project manager assesses the ongoing viability of the project against the business case, including whether the outcomes are likely to deliver the expected performance improvements post-project. This is a continuous process that ensures the project remains aligned with business needs and expected benefits throughout its lifecycle.
PRINCE2 7 Foundation documentation on business case management.

People who join a project after initiation can quickly and easily find comprehensive information about how the project is being managed in the Project Initiation Documentation (PID). The PID provides a detailed basis for the management of the project, including how the project is structured, governed, and what methods are being used. It is a central document that encapsulates all key information needed to understand the project management approach.
PRINCE2 Foundation Manual

The tailoring approach for a project is defined and approved by the project board. This includes adapting PRINCE2 to suit the project's environment, size, complexity, importance, capability, and risk. Tailoring is crucial to ensuring that the project management method is applied in a way that fits the specific characteristics of the project and its context.
PRINCE2 7 Foundation handbook and documents.

The principle that the project manager is applying by reviewing changes in team dynamics is 'Tailor to suit the project context'. This principle involves adapting the management of the project to the environment, including the team dynamics, to ensure that the project management approach is appropriate for the specific context and challenges of the project. References: PRINCE2 7 Foundation handbook and principles section.

The objectives of the 'closing a project' process in PRINCE2 include reviewing whether the project was delivered within time and cost tolerances (2) and confirming whether operational staff are happy to take ownership of the products (3). These objectives ensure the project has met its management expectations and that the product transition to operations is smooth and accepted by relevant stakeholders.
PRINCE2 7 Foundation guide on the 'closing a project' process.