There is every type of opinion in every country. You picked an extreme example that I do not think represents all Trump supporters ( I utterly reject his platform for many reasons myself).
Many declarations about the Trump camp is to re-frame all of their arguments against illegal immigration into anti-immigration, or re-frame it as out-and-out racism. That’s not to say there aren’t racists or racist statements coming from that camp. But misrepresenting every word as racist has had what effect? It lets some pat themselves on the back, but it doesn’t change minds.
The ‘wall’ is about keeping out illegals from (or passing through) Mexico. It certainly wouldn’t have any effect on someone flying in from country X or entering under a visa.