The purpose of this protocol is to evaluate the efficacy and safety of tulisokibart in participants with moderately to severely active Crohn's disease. Study 1's primary hypotheses are that at least 1 tulisokibart dose level is superior to placebo in the proportion of participants achieving clinical remission per Crohn's Disease Activity Index score (\<150, US/FDA) or per stool frequency and abdominal pain score (EU/EMA) and in the proportion of participants achieving endoscopic response at Week 52 (US/FDA and EU/EMA), and that at least 1 tulisokibart dose level is superior to placebo in the proportion of participants achieving clinical remission per Crohn's Disease Activity Index score (\<150, US/FDA) or per stool frequency and abdominal pain score (EU/EMA) and in the proportion of participants achieving endoscopic response at Week 12 (US/FDA and EU/EMA). Study 2's primary hypothesis is that at least 1 tulisokibart dose level is superior to placebo in the proportion of participants achieving clinical remission per Crohn's Disease Activity Index score (\<150, US/FDA) or stool frequency and abdominal pain score (EU/EMA) and in the proportion of participants achieving endoscopic response at Week 12 (US/FDA and EU/EMA).