Most rightwing supporters are driven by their emotions, and fall prey to fear mongering and emotional manipulation related to their already existing beliefs like racism and xenophobia.

To change emotional based beliefs you need to use compassion. They are not your enemy. They are misguided and manipulated souls that need help.

Treat them as your best friend

They won't be open to arguments if they think you're the devil. So you have to be their friend.

It's not necessary to explain everything to them. You can't change someone's world view in one conversation. Just show that you're a reasonable person that is trying to understand them. Gently ask them what their beliefs are and don't be confrontational. With a bit of time they will open their eyes by themselves.

Not easy. but I think that this is what effectively creates change.