Parents' Bill of Rights Act of 2021 This bill establishes various rights of parents and guardians regarding the elementary or secondary school education of their minor children. Specifically, the bill prohibits a state (or its agents, subdivisions, or agents of its subdivisions) from denying certain rights to a parent or guardian of a minor child regarding the child's education. These include, among others, the right to (1) fully review and make copies of the curricula, books, and other educational materials used by the child's school; (2) access information on teachers, guest lecturers, and outside presenters; (3) access school records; and (4) visit the child during school hours. A person aggrieved by a violation of this bill, and a state on behalf of its residents, may bring a civil action for injunctive relief. The bill also requires the Department of Education to withhold federal education funds from a state for noncompliance with this bill.