How to transfer data between iClouds?

[Koyli]

I have an iphone 11, with my mother's old icloud account (she has no data on it), and a mac with my icloud. I want to move my iphone from my old icloud to my mac iCloud, while keeping all the data (messages, photos, health data) if possible. I also have airpods and an apple watch but I think I can just forget those and re-sync to new. Is this possible, and if so, how.

Thank you in advance

 

[mystery hill]

Sign out of your mother’s iCloud account on the iPhone. Then sign in to your iCloud account on the iPhone.