I started CK3 yesterday. It started off great, United Ireland, everyone reasonably happy. Then my heir died of plague, and my grandson became king in a minority, for just over ten minutes until he was deposed. Then he died at age 22, and my zero year old became duke, and he got deposed.

I fear you are about 1hr of game play ahead of me. I am now King of Ireland but have no idea what to do next! I am sure my feldgling dynasty will mean a pitful end very soon.

yup. that's the true CK3 experience!