This study is being carried out in stage III NSCLC which cannot be removed by surgery. In this study, we will identify the effectiveness and safety of a possible treatment combination – durvalumab with domvanalimab, comparing them to durvalumab by itself. Durvalumab by itself is approved for use in NSCLC after the completion of chemotherapy and radiation. Durvalumab (anti-PD-L1) is a type of immunotherapy drug that targets T cells, which are like soldiers that help the body fight infections and other diseases, including cancer. However, cancer cells can escape this attack by expressing a protein called PD-L1. PD-L1 works like a “stop sign” to inactivate T cells. In this way, durvalumab targets cancer cells by blocking the signal that prevents the immune system from seeing the cancer cell. Your immune system can then attack and kill the cancer cells. Domvanalimab (anti-TIGIT) is a type of immunotherapy drug which also targets T-cells by deactivating the TIGIT protein. TIGIT indirectly stops T-cell activation and is expressed on multiple types of immune cells, including T-cells.