Does this sound legal?

I’m not originally from the USA, so American labor laws are a bit strange to me. There is a lot I know you guys don’t protect against.

This is what happened to my coworker not me.

She needed today off, and our boss threatened her and said that she either comes in today or she can hand in her resignation.

That sounds like a way of forcing someone to quit instead of just firing them. Which sounds scummy.

I am curious about what would have happened if she said she’s not coming in and she’s not handing in her resignation,

I guess we’ll find out if that ever happens to me.