How to expand LOV of priority field within PO approval rules?

Summary:I

I'm presented with the need to have higher priorities within the approval rules for purchasing documents.

Specifically on this screen:

Does anyone know if there is a way to add more priorities or change existing ones to manage by numbers?

I was looking for a search but couldn't find one where these values are stored.

I really appreciate your help and comments.

Version (include the version you are using, if applicable):

23C