Grab them up, wire tie hands take to out bound transportation. One they see it is serious, they will begin to self-deport rapidly rather than lose face/be humiliated/etc.
And who is going to do that? CBP and ICE don’t have the bodies to do it and the locals still have to do regular enforcing. Add to that this sanctuary city crap and it’ll be a cluster. Can you do it with those already in custody and incarcerated? Hell yes, and that needs to happen tomorrow. Start there and see where it goes.