A Study Evaluating the Safety and Efficacy of Glofitamab or Mosunetuzumab in Combination With Gemcitabine Plus Oxaliplatin in Participants With Relapsed or Refractory Diffuse Large B-Cell Lymphoma and High-Grade Large B-Cell Lymphoma

Participants will receive intravenous (IV) glofitamab in combination with gemcitabine and oxaliplatin for up to 8 cycles, followed by up to 4 cycles of glofitamab monotherapy.

Participants will receive IV gemcitabine prior to oxaliplatin administration for up to 8 cycles.

Participants will receive IV oxaliplatin after gemcitabine administration for up to 8 cycles.

Participants will receive IV mosunetuzumab in combination with gemcitabine and oxaliplatin for up to 8 cycles.

Participants will receive a single dose of IV obinutuzumab 7 days prior to the first administration of glofitamab.

Participants will receive IV tocilizumab as needed to treat cytokine release syndrome (CRS).