This study looks at how a medicine called **etavopivat** works and if it is safe for kids with sickle cell disease (**SCD**). SCD is a condition where red blood cells, which usually carry oxygen, are shaped like a sickle and can block blood flow. The study is for kids aged 6 months to 18 years. The study will have different age groups, starting with older kids. The study lasts about 96 weeks, which is almost 2 years. During the first 24 weeks, they will check the safety of the medicine, and for the next 72 weeks, they will keep watching to see how it works in the long term. **Key Points to Consider:** - **Study Duration and Visits**: The study lasts for 96 weeks with regular check-ups. - **Eligibility**: Kids must have SCD and meet specific health criteria. - **Exclusion**: Kids receiving certain treatments or with recent severe symptoms may not join. This study can help doctors understand if etavopivat is a good treatment for SCD in kids.