Saguaro National Park Boundary Expansion and Study Act of 2020 This bill modifies the boundary of Saguaro National Park in Arizona by adding approximately 1,232 acres to the park, and it requires the Department of the Interior to conduct a study to identify lands outside the boundaries of the park that may be appropriate for inclusion in the park. The study must be conducted in accordance with criteria of the National Park Service (NPS) for boundary adjustment studies. Interior may, with the consent of Arizona and in accordance with federal and state law, acquire land or interests therein owned by the state within the boundary of the park. If Interior is unable to acquire such state land, Interior may enter into an agreement that would allow the NPS to manage such land within the park's boundary.