The purpose of this study is to learn more about an investigational drug, which is not approved by the United States Food and Drug Administration, called ifinatamab deruxtecan (I-DXd). It is being studied to see if it is safe and if your disease, extensive- stage small cell lung cancer (ES-SCLC), or other medical condition improves while taking it alongside other drugs, Atezolizumab, Carboplatin, and Etoposide. I-DXd is a type of drug called an antibody-drug conjugate, which is made up of 2 parts: an antibody and an anticancer drug. The antibody part binds to a protein commonly found on tumor...