Have to be throwing shade if you want people to back off.
Shoot the, I will end you, kind of look.
I'm usually fine with physical contact from my close friends. To the point we are often asked if we are a couple when we're out, even though when I present as male, I couldn't look more like a fairy

But when I'm out, boy or girl, if someone gets overly familiar, I just tell them to back off. In a mean way usually though so they understand. More often than not, by just shooting them the look I've perfected.