I have a new phone number and a new phone, but my old phone has the old number

No, you cannot switch or change phone numbers through your Apple ID. Apple is not your cell phone service provider. You carrier is. Please contact your carrier and they should be able to resolve the phone number issue for you.

Axel F.

how do I get a new number and don't have my old phone for the new number

Can you change a cell number if your using an e-sim?

It's not entirely clear what you're trying to accomplish.

You can change the trusted phone number associated with the ID if that's what you're trying to ask.