This hypothetical 21st century National Socialist German Workers' Party would likely be a little more subtle than blatantly enforcing existing immigration law. They'd obviously be interested in establishing a common enemy, even if it requires massive exaggeration mixed with complete fabrication. That would do them no good if domestically targeted propaganda were illegal though... hopefully the combination of laws and executive orders preventing that don't get relaxed by the two administrations proceeding this cringy edgelord scenario.