Cannot enable iCloud sync on iPhone after forgetting old passcode

Title: Forgot My Old iPhone Passcode and Cannot Enable iCloud Sync

Hello Apple Community,

I recently signed back into my Apple Account on my iPhone. However, when I try to enable iCloud sync, my iPhone asks me to enter the passcode of my previous iPhone, which I have forgotten.

I know my Apple Account password and can access my account, but I cannot remember the old iPhone’s passcode.

I want to keep my existing data on my current iPhone and sync my data with iCloud without losing my photos, contacts, and other important information.

Is there a safe way to resolve this issue without losing my existing data?

I would appreciate any help or advice.

Thank you.