But if they don't submit willingly, they are killed.
Sura (9:29) - "Fight those who believe not in Allah nor the Last Day, nor hold that forbidden which hath been forbidden by Allah and His Messenger, nor acknowledge the religion of Truth, even if they are of the People of the Book, until they pay the Jizya with willing submission, and feel themselves subdued."
Like I said, they’re made into dhimmis. Second class citizens.
As with other regimes that impose second class citizen status, such as apartheid and the Jim Crow south, those who refuse to accept this status are likely to get themselves killed.