A Phase 3, Randomized, Open-label, Multicenter Clinical Study to Evaluate the Safety and Efficacy of MK-1084, Cetuximab, and mFOLFOX6 Versus mFOLFOX6 With or Without Bevacizumab as First-line Treatment of Participants With KRAS G12C-mutant, Locally Advanced Unresectable or Metastatic Colorectal Cancer (KANDLELIT-012)

Inclusion Criteria: The main inclusion criteria include but are not limited to the following: * Has a histologically confirmed diagnosis of locally advanced unresectable or metastatic (unresectable Stage III or Stage IV as defined by American Joint Committee on Cancer \[AJCC\] eighth edition) colorectal adenocarcinoma * Part 2 only: Has not received systemic anticancer therapy for locally advanced unresectable or metastatic colorectal cancer; an exception is permitted for 1-2 cycles of FOLFOX or 1 cycle of CAPOX as optional chemotherapy before or during the screening period * Demonstrates presence of a Kirsten rat sarcoma viral oncogene homolog G12C (KRAS G12C) mutation * Human immunodeficiency virus (HIV)-infected participants must have well controlled HIV on antiretroviral therapy (ART) * Participants who are Hepatitis B surface antigen (HBsAg) positive are eligible if they have received hepatitis B virus (HBV) antiviral therapy and have undetectable HBV viral load * Participants with history of hepatitis C virus (HCV) infection are eligible if HCV viral load is undetectable Exclusion Criteria: The main exclusion criteria include but are not limited to the following: * Has active inflammatory bowel disease requiring immunosuppressive medication or previous clear history of inflammatory bowel disease (eg, Crohn's disease, ulcerative colitis, chronic diarrhea) * Has uncontrolled, significant cardiovascular disease or cerebrovascular disease * Has known partial or complete dihydropyrimidine dehydrogenase (DPD) deficiency * HIV-infected participants with a history of Kaposi's sarcoma and/or Multicentric Castleman's Disease * Has received prior systemic anticancer therapy including investigational agents within 4 weeks before randomization, with the exception of the optional chemotherapy * Has 1 or more conditions that, in the opinion of the investigator, make the participant ineligible for treatment with bevacizumab * Has known additional malignancy that is progressing or has required active treatment within the past 3 years * Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis or leptomeningeal disease * Has active infection requiring systemic therapy * Has not adequately recovered from major surgery or have ongoing surgical complications * Has a history of (noninfectious) pneumonitis/interstitial lung disease that required steroids or has current pneumonitis/interstitial lung disease