Two factor authentication problem
I can't sign in to an Apple ID as it requires two factor authentication with a code being sent to a phone number I don't recognise and don't believe I ever set up.
You'll need to get a verification code on your trusted device.
Get a verification code and sign in with two-factor authentication https://support.apple.com/en-us/HT204974
There are a few ways you can get a verification code. You can use the code displayed on your trusted device, get a text or phone call, or generate a code from your trusted device.” A trusted device is an iPhone, iPad, or iPod Touch with iOS 9 and later or a Mac with OS X El Capitan and later that you've already signed into using two-factor authentication.