Cemiplimab and Quad Shot Radiation for Cutaneous Squamous Cell Carcinoma in the Head and Neck

The goal of this clinical trial is to learn if the combination of the drug cemiplimab along with a short course of radiation therapy called Quad Shot can be successfully given in several rounds to elderly or frail patients with head and neck skin cancers. The main question it aims to answer is: \- Can care providers successfully deliver at least 6 rounds of cemiplimab and 3 rounds of Quad Shot radiation to patients? Patients will: * Be given cemiplimab every 3 weeks for a total of up to 8 doses * Be given Quad Shot radiation (four treatments over two days) every 3 weeks for a total of up to 4 rounds