The main inclusion criteria include but are not limited to the following: - Has histologically documented urothelial carcinoma (UC) that is locally advanced and unresectable or metastatic - Must provide a newly obtained or archival tumor tissue sample (core or excisional biopsy) - Must not have received prior systemic therapy for locally advanced or metastatic UC - If infected with Human Immunodeficiency Virus (HIV), has well controlled HIV on antiretroviral therapy - If positive for hepatitis B surface antigen, has received hepatitis B virus (HBV) antiviral therapy for at least 4 weeks and has undetectable HBV viral load before randomization - If participant has a history of hepatitis C virus (HCV), has undetectable HCV viral load before randomization

The main exclusion criteria include but are not limited to the following: - Has history of documented severe dry eye syndrome, severe Meibomian gland disease and/or blepharitis, or corneal disease that prevents/delays corneal healing - Has active keratitis or corneal ulcerations - Has active inflammatory bowel disease requiring immunosuppressive medication, or previous history of inflammatory bowel disease (eg, Crohn's disease, ulcerative colitis, or chronic diarrhea) - Has uncontrolled, significant cardiovascular disease or cerebrovascular disease within the 6 months preceding study intervention - Has a history of uncontrolled diabetes - Has pleural effusion, ascites, and/or pericardial effusion that are symptomatic or require repeated drainage - Has active autoimmune disease that has required systemic treatment in the past 2 years - Has known additional malignancy that is progressing or has required active treatment within the past 2 years - Has known active central nervous system metastases and/or carcinomatous meningitis - Has a history of (noninfectious) pneumonitis/interstitial lung disease that required steroids, or has current pneumonitis/interstitial lung disease - Has an active infection requiring systemic therapy - If infected with HIV, has a history of Kaposi's sarcoma and/or Multicentric Castleman's Disease - Has concurrent active HBV and HCV infection - Has a history of stem cell/solid organ transplant