Study Comparing BGB-B2033 With Sorafenib or Lenvatinib in Relapsed Hepatocellular Carcinoma

The goal of this clinical trial is to learn how well BGB-B2033 works and how safe it is in people with hepatocellular carcinoma (HCC) who have previously received up to two treatments that included programmed cell death protein 1 (PD-1)/programmed death ligand 1 (PD-L1) medicines. Researchers will compare BGB-B2033 with either sorafenib or lenvatinib chosen by the study doctor to see which treatment works better and is safer. The main questions it aims to answer are: * Does BGB-B2033 help control or slow the growth of liver cancer? * What medical problems or side effects do participants have while taking BGB-B2033? * Does BGB-B2033 help to prolong the survival for liver cancer participants over Lenvatinib/sorafenib?

Key Inclusion Criteria: 1. Participants must have histologically confirmed Hepatocellular Carcinoma (HCC) that is not amenable to curative surgical or locoregional therapies. 2. Participants must have documented disease progression or intolerance after at least 1 but not exceeding 2 prior lines of systemic therapy containing Programmed Cell Death Protein 1 / Programmed Death-Ligand 1 (PD-1/PD-L1). Prior cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) targeting therapy or v ascular endothelial growth factor (VEGF) is permitted but not required. 3. Glypican-3 (GPC3) expression level must be known for stratification. 4. Participants must have at least 1 measurable lesion as assessed by RECIST v1.1 5. Participants must have a stable Eastern Cooperative Oncology Group (ECOG) Performance Status of ≤ 1. Key Exclusion Criteria: 1. Prior therapy targeting GPC3 or 4-1BB 2. Participants not feasible to be treated with lenvatinib or sorafenib 1. prior exposure to both medications 2. siginificant precautions of administering lenvatinib or sorafenib such as clinically significant active bleeding within 3 months prior to first dose, tumor thombus involving main portal vein trunk, inferior vena cava, or cardiac involvement, 3. any history of gastrointestinal perforation or larger than grade 3 fistula within 6 months prior to the first dose, 4. or any history of heart failure meeting NYHA classification III or IV ≤ 6 months before the first dose of study drug. 3. Active leptomeningeal disease or uncontrolled and untreated brain metastasis 4. History of previous or present encephalopathy 5. Presence of clinically significant ascites ((≥ Grade 2). 6. History of liver transplantation NOTE: Other eligbility criteria may apply.