Seems your Apple ID can be used to sign-in to iCloud.
You likely used it to sign-in here to the Apple Community, and may use it for FaceTime and Messages etc.
(Apple ID is generally an email address ... you say you know the password.)
You can check if you are signed in (to your device) with your Apple ID: Sign in with your Apple ID - Apple Support
Else:
If you have another computer or device listed with the same Apple ID:
you may be able to get a verification code on that computer or device and update the phone details online:
Apple ID Log-in:
https://appleid.apple.com/
How to: Get a verification code and sign in with two-factor authentication - Apple Support
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Else: If the iPhone was the only device listed in your Apple ID:
You may be able to recover your account (takes a few days) by proving your identity to Apple:
(Use account recovery only as a last resort when you can’t sign in or reset your Apple ID password.)
How to use account recovery when you can’t reset your Apple ID password - Apple Support
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If more help is needed:
Apple ID Support website (info. / support / contact options):
Apple ID - Official Apple Support
See a list of Apple phone numbers around the world
Contact Apple for support and service - Apple Support