Your manager is not your friend, although they pretended to be. Do not offer to volunteer, because there will be low-performer quotas to fill in the future and they will unexpectedly create a low-performer review for you with vague language about all these previously undocumented performance issues you were never informed of.
Post ID @3ezl+1kqmCgCU. This is good advice!
Do new grads get rated too?
Yes, managers aren't your friend. Never treat them as one. If you're unwilling to support overtime, be prepared to get a rating 2. The company says overtime is voluntary but you'll get your ratings docked because presumably your lack of overtime indicates your unwillingness to perform. Also there are some people given a low rating because they were told it's their turn this year. And participating in continuous improvement projects doesn't guarantee you're safe from being lowly rated. There was a culture champion who saved the company thousands of dollars and was given a rating 2 because well, he was slow in his work.