Well, that will have to do until they can get the right case before the SCOTUS telling us that the 13th amendment really doesn't mean that slavery is illegal.
Actually, that's hyperbole on my part. They're going to use the 13th Amendment as it's already written:
"Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction."
Bingo-bango, easy-peasy, here's the plan: arrest all the brown people. Charge them with immigration crimes. Convict them en masse. Incarcerate them in "camps" near agricultural sites. Bus them to the farms, where they will do the exact same work they were doing before, except THIS time, they won't be getting paid. The farm corporation will pay the government for their labor (paying way less than they were getting paid before). Winner: Trumpco, which will collect payments for the brown convict slave labor. Winner: Ag corps, which will get the same labor as before, but at a reduce price. Loser: dirty brown people, but who cares, they aren't human anyway.