This study is testing how two new drugs, CagriSema and cagrilintide, help kids aged 8 to 18 who have extra body weight to lose weight. The study consists of two parts: a main study and an extension study. In the main study, participants may receive either of the new drugs, semaglutide (a drug already approved by doctors), or a placebo (which looks like a drug but has no active ingredients). The treatment each participant gets is chosen randomly. The main study lasts about 1 year and 6 months. Participants who continue to the extension study will receive either CagriSema or cagrilintide, and this part lasts about 4 years and 10 months. **Study drugs may have side effects.** **Key Points:** - **Duration:** Main study lasts 1 year and 6 months; if continuing, extension study lasts 4 years and 10 months. - **Visit Requirements:** Regular visits for check-ups and monitoring. - **Eligibility:** Participants must have tried to lose weight before joining and meet certain health criteria. This study aims to provide more options for weight management for children but requires a long-term commitment. Participation involves random treatment assignment and requires parental consent.