I was the first in this forum to assert that which must be done:
The administration must send in ICE and federal officials, backed by government troops, to arrest those at the top levels of such cities, including arrest at the threat of gunpoint if that is required. And if the cities (or states) put local or state police in the way of such arrests, they must be removed -- by force, if required. And then prosecuted as well.
Call it a "Little Rock, 1957, moment" if you wish.
But short of this there is no other way to effectively force these cities (and a few states) to comply with immigration laws.