As an immediate step, President Trump should direct all government agencies to pull meetings, conferences, and travel from California and any state giving sanctuary to illegal aliens. This is simple, a part of day-to-day government operations, not something requiring congressional action, nor reviewable by courts. Heck, Obama did the same when he discouraged travel to Las Vegas. President Trump should do the same with California and others. Action, not words.
And freeze new employment in those states and localities, relocate new workers to other places. See how long California, Chicago, and others hold out. Make an example of California and scare the others back into compliance.