A Study to Learn About Study Medicine Called PF-08049820 in People With Eczema

The purpose of this study is to learn if the study medicine (PF-08049820) is safe and effective for the treatment of atopic dermatitis (AD), also known as eczema, or atopic eczema. People with this condition may have severe itching and rashes on the skin. The study is seeking participants who: 1. Are aged 18 years or older; 2. Were confirmed to have AD at least 6 months ago; 3. Do not have a suitable prescribed medicine for AD; 4. Are considered by their doctors to have moderate to severe AD. The study has two stages (Stage 1 and Stage 2). In both stages, eligible participants will take either PF-08049820 or placebo as tablets by mouth daily for 12 weeks. A placebo does not have any medicine in it but looks just like the medicine being studied. Participants will visit the clinic on Day 1, Weeks 1, 2, 4, 6, 8 and 12. They will have a follow-up visit at Week 16. During this time, the participant's health and skin condition will be checked. They will have blood and urine tests. They will also have to answer questions about their health, skin condition, and how much their skin condition affects their lives. The experiences of participants receiving the study medicine will be compared to those receiving placebo. This will help to understand if PF-08049820 is safe and effective.