Researchers are looking for other ways to treat relapsed high-grade serous ovarian cancer. Relapsed means the cancer came back after treatment. High-grade means the cancer cells grow and spread quickly. Serous means the cancer started in the cells that cover the ovaries, the lining of the belly, or in the fallopian tubes. Standard treatment (usual treatment) for people with relapsed high-grade serous ovarian cancer may include: * Chemotherapy, which is a treatment that uses medicine to destroy cancer cells or stop them from growing * Targeted therapy, which is a treatment that works to control how specific types of cancer cells grow and spread Raludotatug deruxtecan (R-DXd) is a study treatment that is an antibody drug conjugate (ADC). An ADC attaches to a protein on cancer cells and delivers treatment to destroy those cells. Researchers want to know if R-DXd is safe to take with other treatments and if people tolerate them together. They also want to learn how many people have the cancer respond (gets smaller or goes away) to the treatments.