There is no canonical answer to this question. A project manager might report to:
* The PMO for the organization.
* A steering committee.
* The project sponsor.
* The line manager or executive responsible for the project's deliverables.
* A customer-facing engagement manager.
* The budgeting authority for the project.
* All of the above.
Other answers are also possible. Not only is the reporting structure variable, but the scope of the role and its "authority" (real or imagined) are also highly variable between frameworks and organizations. In short, your mileage will vary.