Should I negotiate my severance? after 9 years as an administrative assistant

My manager said the package is final, but the letter gives me time to review. Any experience at all would help. I do not want to leave money on the table. Should I see a lawyer?

Ask for the offer in writing and do not sign on the spot. A day or two to think is normal.

I asked for two more weeks and a neutral reference. They agreed to the reference and added a week.