New iphone old icloud
Can my existing/old icloud account work with my new iphone if I changed my phone number? Also I lost my old iphone.
You may require account recovery to regain entry to that account - Two-factor authentication for Apple ID - Apple Support.
"If I can't sign in, how do I regain access to my account?
If you can’t sign in, access a trusted device, reset your password, or receive verification codes, you can request account recovery to regain access to your account."