No. Opt-out is exactly the wrong approach. Instead consider a flag indicating that "I'm OK with mu source being used for training AI models." i.e. opt-in.
ADDED: To be clear, it may be fine to say that making certain things opt-in means that other things that many might value can't exist.
This isn't the problem, it's the whole point.
Things need to be made opt-in because we want there to be a meaningful barrier to companies using data that does not belong to them in order to make money.