Might get put on PIP. what can I do where it turns in my favor

I understand PIP is basically where a company leaves a paper trail for them to justify in firing you so they can fight against unemployment claims. I have a suspicion that I might be placed on PIP. What happens if I try to refuse to sign it and if they do make me sign it, can I just have them write a written agreement that they can’t fight my unemployment first in case they terminate me after PIP?