The main purpose of the SYNERGY-OUTCOMES study is to find out whether retatrutide and tirzepatide can prevent major adverse liver outcomes (MALO) in people with high-risk metabolic dysfunction-associated steatotic liver disease (MASLD). The study will enroll adults who have MASLD based on non-invasive tests (NITs), which indicate they are more likely to develop MALO. Participants will be randomly assigned within a Master Protocol to receive either retatrutide (N1T-MC-RT01), tirzepatide (N1T-MC-TZ01) or placebo. The trial plans to enroll about 4,500 adults and will run for approximately 224 weeks. Participants may have up to approximately 25 to 30 clinic visits throughout the study to monitor their health, complete study procedures, and assess liver function and disease progression. Once the study is complete, eligible participants may participate in an optional 2-year extension study, in which all participants will receive either retatrutide or tirzepatide, even if they received placebo in the main study.