Key Inclusion Criteria:  Eastern Cooperative Oncology Group Performance Status of 0 or 1. Histologically confirmed esophageal squamous cell carcinoma (ESCC). Stage cT1-2N+M0 and cT3NanyM0 (per The American Joint Committee on Cancer 8th Edition). Evaluation by the investigator to confirm eligibility for an R0 resection with curative intent. Adequate hematologic and organ function, defined by protocol-specified laboratory test results obtained within 14 days before first dose.  Key Exclusion Criteria:  Ineligible for treatment with any of the chemotherapy doublets of protocol-specified chemotherapy. Any prior therapy for current ESCC, including investigational agents, chemotherapy, radiotherapy, or prior therapy with an anti-programmed cell death protein-1, anti-programmed cell death protein ligand-1, anti-programmed cell death protein ligand-2, or any other antibody or drug specifically targeting T-Cell co-stimulation or checkpoint pathways. History of fistula due to primary tumor invasion. Participants with high risk of fistula or sign of perforation evaluated by investigator.  Any condition requiring systemic treatment with either corticosteroids (> 10 mg daily prednisone or equivalent) or other immunosuppressive medications within 14 days before first dose.  * Adrenal replacement steroid (dose ≤ 10 mg daily of prednisone or equivalent) and topical, ocular, intra-articular, intranasal, or inhaled corticosteroid with minimal systemic absorption, and short course (≤ 7 days) of corticosteroid prescribed prophylactically or for the treatment of a non-autoimmune condition are permitted.  Active autoimmune diseases or history of autoimmune diseases that may relapse.  * Controlled Type I diabetes, hypothyroidism only requiring hormone replacement, controlled celiac disease, skin diseases (such as vitiligo, psoriasis, or alopecia) not requiring systemic treatment, or conditions not expected to recur in the absence of an external trigger are permitted to enroll.  History of interstitial lung disease, non-infectious pneumonitis or uncontrolled diseases including pulmonary fibrosis, acute lung diseases.  With infections requiring systemic antibacterial, antifungal, or antiviral therapy, including tuberculosis infection.  Severe infections within 4 weeks before first dose, including but not limited to hospitalization for complications of infection, bacteremia, or severe pneumonia. Receive therapeutic oral or intravenous antibiotics within 2 weeks before first dose.  Note: Other protocol defined Inclusion/Exclusion criteria may apply.