I experimented with this briefly, and if you have the iCloud entitlement with a CloudKit container selected it does automatically sync. However it still has all the same restrictions Core Data has for CloudKit integration such as not supporting attributes like Unique. In the same vein, I have yet to see any sort of Persistent History delegates or observations with SwiftData, such as in my case I have to deduplicate entries because of the lack of unique attributes in CloudKit. So overall it's great API for simple data models, but quickly runs into needing to drop back to Core Data for anything more realistic.