No — in an iMessage group chat, someone added back usually only sees messages sent after they rejoin, not the older message history. Apple forum guidance says the thread is visible only from the point they were added.

What that means

  • If they were removed, they generally won’t see the messages from the time they were out of the chat.
  • If someone sends new messages after they’re added back, those new messages should appear normally for them.
  • This is different from some other chat apps that can optionally share history when someone joins.

Small caveat

If they already had screenshots, copied messages, or another device/account that still showed the thread, that’s separate from what the live group chat itself reveals. But as a rule, the re-added person does not get the old iMessage history back.