I forgot my iPhone xr apple id and password and recovery key

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 -> If you can't connect or sign in to iCloud

If you can't connect or sign in to iCloud - Apple Support

See -> Two-step verification for Apple ID

Two-step verification for Apple ID

👉 scroll to & read -> What if I lose my Recovery Key?

You can sign in to your Apple ID account page and create a new Recovery Key using your Apple ID password and one of your trusted devices.

1 Go to appleid.apple.com/uk.

2 Sign in with your password and trusted device.

3 In the Sign-In and Security section, click Recovery Key > Change Recovery Key.

Keep your new Recovery Key in a safe place. Your old Recovery Key won't work any more and you can't use it to reset your password or access your account. If you can't see Recovery Key in the Sign-In and Security section, then you are not using two-step verification. 

FYI: Make a screenshot or write down your recovery key and keep it in a safe place.