How does Apple's mobile phone send short messages in groups?

Apple's mobile phone group SMS method is as follows:

Tools/materials: iPhone 12, IOS 15.2, SMS.

1, turn on the SMS function.

2. Open the email and click? "Post-it notes"? Icon to enter the edit SMS page.

3. click? On the right side of the recipient column. "+"? Icon.

4. Click the contact who wants to send a group message. Only one person can be added at a time.

5. After editing the message, click? Send icon to complete batch sending.