The purpose of this study is to compare anti-tumor activity of amivantamab in addition to pembrolizumab and carboplatin versus pembrolizumab, 5-fluorouracil (FU), and platinum therapy (carboplatin or cisplatin) in participants with refractory/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC). HNSCC is a type of cancer that develops in the head and neck regions, including the outer tissue layer of the mouth and throat. This study will focus on participants with HNSCC who are treatment-naive (have not received prior treatment) in the R/M setting.