Can I pay medical insurance only after social security is done?

1. Pension, medical care and unemployment are indispensable, which can dispel the idea of just buying something.

2. If you have a unit, the personnel manager of the unit will handle it.

If you are an individual, you need a household registration book, an ID card and a bank passbook designated by the local social security bureau (for deduction). It seems that individuals can choose grades before insurance. Some time ago, new regulations were introduced. I wonder if they can choose grades now.