As far as I know its The Coleraine conspiracy, The Apprentice Boys and The Sunningdale Agreement. These are the document based questions. There are a ton of case studies overall, some I found to be interesting were Stalin's show trials, Johnson and Vietnam, and the first moon landing. I thought the Irish history ones werent all that interesting. As far as I know they arent changing for the 2023 paper but Im sitting 2022 so im not all that sure
I don't know what topics you are covering but for definite, you need to know the 3 Northern Ireland Case Studies for the Document Question.
My teacher told me you are always better off knowing all the case studies of the sections you study In our school, we have done Soveirngty and Partition, Dictatorship and Democracy and The United States and the World and have done most case studies out of all three of sections, other than the Vietnam War. They are easy enough to conquer and a question is asked on one or two of them each year.