A Study to Evaluate the Safety and Pharmacokinetics of the Intravenous Fixed-Dose Combination (IV FDC) of Tiragolumab and Atezolizumab in Participants With Locally Advanced, Recurrent or Metastatic Solid Tumors

Inclusion Criteria: * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1 * Life expectancy \>=12 weeks * Adequate hematologic and end organ function * Recovery (i.e., improvement to Grade 1 or better) from all acute toxicities from previous therapy, excluding alopecia * For female participants of childbearing potential, negative serum pregnancy test within 14 days prior to initiation of study treatment (Day 1 of Cycle 1) * For female participants of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraception, and agree to refrain from donating eggs during the treatment period and for 5 months after the final dose of tiragolumab and atezolizumab IV FDC * For male participants: agreement to remain abstinent (refrain from heterosexual intercourse) or use a condom, and agree to refrain from donating sperm during the treatment period and for 90 days after the final dose of tiragolumab and atezolizumab IV FDC to avoid exposing the embryo Cancer-Specific Inclusion Criteria: * Histologic documentation of locally advanced, recurrent, or metastatic malignancy, ineligible for definitive local therapy, for which a clinical trial of an investigational agent in combination with an anti-PD-L1 antibody is considered an acceptable treatment option. Participant must be informed of all standard of care options available for his/her cancer. * No prior treatment with checkpoint inhibitor therapies (CPI-Naive) * Measurable disease per Response Evaluation Criteria in Solid Tumors, Version 1.1 (RECIST v1.1) * Submittal of archival tumor and/or fresh tumor tissue to the central laboratory for programmed death-1 (PD-L1) evaluation prior to enrollment * PD-L1 selected tumors, as determined by the investigational VENTANA PD-L1 (SP263) immunohistochemistry (IHC) assay Exclusion Criteria: * Pregnancy or breastfeeding, or intention of becoming pregnant during the study or within 5 months after the final dose of tiragolumab and atezolizumab IV FDC * Significant cardiovascular disease * Known clinically significant liver disease * Poorly controlled Type 2 diabetes mellitus * Major surgical procedure within 28 days prior to Day 1 of Cycle 1 or anticipation of need for a major surgical procedure during the study * Any other diseases, metabolic dysfunction, physical examination finding, and/or clinical laboratory finding giving reasonable suspicion of a disease or condition that contraindicates the use of an investigational drug or that may affect the interpretation of the results or may render the participant at high risk from treatment complications * History of autoimmune disease * Treatment with systemic immunosuppressive medications within 2 weeks prior to Day 1 of Cycle 1 * History of idiopathic pulmonary fibrosis, pneumonitis, organizing pneumonia, or evidence of active pneumonitis on screening chest computed tomography (CT) scan * Severe infections within 4 weeks prior to Day 1 of Cycle 1 or recent infections/oral or IV antibiotics within 2 weeks prior to Day 1 of Cycle 1 Cancer-Specific Exclusion Criteria: * Any anti-cancer therapy, whether investigational or approved within 3 weeks prior to initiation of study treatment * Prior treatment with immune checkpoint inhibitors (CPIs) * Less than 5 drug-elimination half-lives (\~100 days for typical monoclonal antibody \[Mab\]) from the last dose of monoclonal antibodies (MAbs), and MAb-Derived Therapies (excluding CPIs) and the proposed Day 1 of Cycle 1 * Less than 6 weeks between the last dose of prior immunomodulators and the proposed Day 1 of Cycle 1 * Less than 6 weeks or 5-drug-elimination half-lives, whichever is shorter, of prior treatment with cancer vaccines and/or cytokines have elapsed between the last dose and the proposed Cycle 1, Day 1 * Any history of an immune-mediated Grade 4 adverse event attributed to prior cancer immunotherapy * Any history of an immune-mediated Grade 3 adverse event attributed to prior cancer immunotherapy that resulted in permanent discontinuation of the prior immunotherapeutic agent and/or occurred \</=6 months prior to Day 1 of Cycle 1 * Any immune-mediated adverse events related to prior cancer immunotherapy must have resolved completely to baseline * Adverse events from prior anti-cancer therapy that have not resolved to Grade \<=1 except for alopecia, vitiligo, or endocrinopathy managed with replacement therapy