Update Apple Id Settings requires iPhone passcode and I don't have the phone any more

I don't think it is asking for the iPhone passcode, it is asking for a verification code that is being sent to your trusted devices. What's puzzling is you iPad should be also getting the code.

Read the articles Two-factor authentication for Apple ID - Apple Support ) and Get a verification code and sign in with two-factor authentication - Apple Support . Various sections contain information that is useful in understanding about the trusted devices (an iPhone, iPad, or Mac that Apple knows is yours) system, and how to get a verification code on a trusted device or at a telephone number.

You can look into adding more ways to get a code such as multiple telephone numbers where you can receive a text or a phone call. This is from the section "About trusted phone numbers and trusted devices" in the article: Two-factor authentication for Apple ID - Apple Support :

To see, add, or change your trusted phone numbers use one of these methods:

● On your iPhone, iPad, or iPod touch: Go to Settings > your name > Password & Security. Next to Trusted Phone Number, tap Edit.

● On a Mac computer choose Apple menu  > System Settings (or System Preferences), then click your name (or Apple ID). Click Password & Security, then add or remove a trusted phone number.

● Using a web browser: Go to the Account Security section of https://appleid.apple.com .

If you had set up an Account Recovery Contact ( Set up an account recovery contact - Apple Support ) you can also get a code that way.

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. This article explains how to recover your Apple ID after a waiting period - How to use account recovery when you can’t reset your Apple ID password - Apple Support

One thing Apple says in much of its trouble shooting documentation and in the ersponses made by community specialists on the forums is make sure your software is up to date. That's not to say this is an absolute must (frankly everything I own is well outside of Apple's support time window), but they don't want an issue to be caused my an old piece of software no longer knowing how to interact with something new.

You're right, it does say that. I think Apple is allowing some shortcuts these days in terms of verification between trusted devices. It is odd that your iPad is not considered a trusted device sine I presume you use the same Apple ID on that and have signed in on it. Try adding a telephone number which can be any kind of telephone. I am presuming you can still log into your Apple ID (many people who post here are in a mess because they have forgotten their log-in information and have no trusted devices).