This study is designed to test the effectiveness and safety of a new drug combination, **divarasib and pembrolizumab**, compared to the current standard drugs **pembrolizumab, pemetrexed, and carboplatin or cisplatin**. It's for adults with a specific type of lung cancer called **KRAS G12C-mutated, advanced or metastatic non-squamous non-small cell lung cancer (NSCLC)**. Advanced means the cancer has spread and is not suitable for surgery. **Key Points:** - Participants must have a KRAS G12C mutation and no prior treatment for advanced NSCLC. - Some health conditions and previous treatments (like other cancer therapies or certain medications) may disqualify participation. - The study involves comparing the new drug combination against existing treatment options. If you are eligible, you might get access to a potentially better treatment. However, participation involves regular health check-ups and monitoring during the treatment period. Your participation can help advance cancer research and potentially improve future treatments.