That's the defining feature of a boundary: you don't actually tell people what to do. You just tell them what you'll do. "Don't talk to me like that" is an ask,

That's the defining feature of a boundary: you don't actually tell people what to do. You just tell them what you'll do. "Don't talk to me like that" is an ask, "Talk to me like that again and I'll leave" is a boundary.