How does "asymmetric elliptical key (using P-256) derived from the user’s iCloud account password" generated and synced to every device?

I just read the "Apple Platform Security Guide 2024" and find the description in iCloud Keychain Chaptor:

"When a user turns on iCloud Keychain for the first time on a two-factor authentication

account, the device establishes and creates a syncing identity for itself. The syncing

identity consists of asymmetric elliptical keys (using P-384), which are stored in the

device’s keychain. Each device maintains its own list of syncing identities of the user’s

other devices, and signs this list using one of its identity keys. These lists are stored in

CloudKit, allowing the user’s devices to reach consensus on how to securely sync keychain

data between themselves.

For compatibility with older iCloud devices, a similar syncing circle of trust is created

and another syncing identity is formed. The public key of the syncing identity is put in

the circle, and the circle is signed twice: first by the private key of the syncing identity,

and then again with an asymmetric elliptical key (using P-256) derived from the user’s

iCloud account password. Also stored with the circle are the parameters (random salt and

iterations) used to create the key that’s based on the user’s iCloud password."

Just want to know how the keypair(an asymmetric elliptical key (using P-256) derived from the user’s

iCloud account password) generated and synced to every device with the same Apple Account.

Thank you very much

Rock3