What if I am fired from a Henry job?

Hi everyone , I am lucky enough to be holding down a Henry job for a few years now. It is an American company; so I constantly worry about being fired anytime. :(

I want to know if any one have any success stories in negotiating a severance package when being let go? a. For instance can I ask them to cash out my unvested RSUs? (I have got over $200k locked up there) b. Can I ask them to continue some benefits. (I actively use a benefit called carrot fertility which pays for my IVF upto to a certain amount)

What other things could I ask for?

PS: I think I might be greedy here,, but I don't want to miss out on something just because I didn't ask for it.