One thing I try to do with, I don't know let's call them, normies, is to just appeal to their self-interest.
Like you got to know the fascists aren't going to stop with the trans people, that's just the people WE decided were acceptable to sacrifice for our comfort.
The reason you need to fight for trans people, even if you aren't trans, even if you're bigoted against trans people, is because they're going to get to you eventually.
Appealing to people's humanity is sadly less effective.