Account Subscription
Account subscription is one of the Subscription functions, and it is a function that allows you to stream the latest public posts of the target account to the home timeline or list by a mechanism different from follow. (Note: The UI to add account subscriptions to the list is not currently enabled) You can specify any account, but you can subscribe only if the account exists, is not following, and is not blocked by the other person. You can also subscribe to follow-approval accounts.
Rely on a federated timeline and receive a post if someone follows, is forwarded by a relay, or someone boosts or fetches, so you can receive a post if you don't meet the criteria can not.
Subscriptions are essentially a federation of the federation timeline, so what you subscribe to will not be disclosed and you will not be notified.