This study will enroll adult participants with early-stage (stage II-IIIB) non-small cell lung cancer for whom surgery is planned. The aim is to find out whether an investigational treatment (consisting of the immunotherapy drug cemiplimab plus chemotherapy plus a third drug) works better than cemiplimab plus chemotherapy without the additional drug. The study is also looking at several other research questions, including: * What are the side effects associated with the investigational treatments in comparison to the control treatment? * Do the investigational treatments or the control treatment have an effect on the type of surgery that is performed? * How much of the study drug(s) are in the blood at a given time? * Does the body make antibodies against the study drug(s) (which could make the drug(s) less effective or could lead to side effects)?