Study to Evaluate Soquelitinib in Participants With Moderate to Severe AD

The main purpose of this study is to see how well different doses of soquelitinib work in participants with atopic dermatitis (AD) as compared to a placebo (pill with no medicine in it). To check this, the study doctors will examine participants' skin regularly to track how their AD changes during the study. The study doctors will see how safe soquelitinib is by tracking side effects among participants. They will also check "tolerability," which means how well the participants can handle soquelitinib and whether any potential side effects are manageable for them. To understand how well soquelitinib works, it will be compared with a placebo. Placebo is a substance that looks like soquelitinib but contains no active medicine in it. Participants will: * Take study treatment (soquelitinib or placebo) every day for 12 weeks * Visit the clinic for check-ups and tests every week for the first 2 weeks then every 2 weeks during the treatment period, and then return for follow-up visits 30, 60, and 90 days after the last dose of study treatment