Nivolumab and Combination Chemotherapy in Treating Participants With Diffuse Large B-Cell Lymphoma

Inclusion Criteria: * Patient must have a confirmed diagnosis of: * De novo DLBCL including the clinical subtypes of primary mediastinal, - cell/histiocyte-rich large B-cell lymphoma and intravascular DLBCL OR * De novo transformed DLBCL from follicular lymphoma (FL) OR * Any high grade CD20+ B-cell lymphoma per World Health Organization (WHO) 2016 OR * CD20+ aggressive B-cell lymphoma unclassifiable. * Patient must be deemed an appropriate candidate for R-CHOP therapy. * Patients must be naive to prior therapy for the study diagnosis. * Patient must have advanced stage III/IV early stage disease where provider determines single modality therapy with chemo-immunotherapy is most appropriate (i.e radiation deferred). * Patient must have measurable disease (defined as \>= 1.5 cm in diameter) with correlated fludeoxyglucose F-18 (FDG)-avidity on positron emission tomography (PET) scan with Deauville score of 4 or 5 at time of diagnosis. * Patient must have Eastern Cooperative Oncology Group (ECOG) performance status =\< 2. * Absolute neutrophil count (ANC) \>= 1000/mm\^3, independent of growth factor support or \>= 500/mm\^3 in cases of ongoing bone marrow involvement (in either case, these must be independent of transfusion support) documented =\< 28 days prior to registration. * Platelets \>= 100,000/mm\^3, or \>= 50,000 in cases of ongoing bone marrow involvement (In either case, these must be independent of transfusion support) documented =\< 28 days prior to regist…