I want another Apple ID to use this iPhone

You are sign in here .  .  .  with your Apple ID & Password.

Your Apple ID is the personal account you use with all Apple products and services. It includes the email address and password you use to sign in, as well as the contact, payment, and security details that you use with Apple.

You can’t merge multiple Apple ID accounts.

See -> Related Article -> If you see a Could Not Create Apple ID or Could Not Set Up iCloud message

What is the purpose behind this requirement? Do you want to give or sell this iPhone to another person and remove your Apple ID so that the new owner can put his/hers on it? Do you want to lend your iPhone to someone for a while? Or do you want to share one phone between two people, much as you might share a desktop computer?