My trusted phone number

See this thread How to find my phone - Apple Community

It is possible that the old trusted number is not verified / blocked in the server account , you can add a new trusted number and then follow the steps ( once Apple ID password is reset ) , follow the steps .

To set up old iCloud account in new iPhone .

The Apple ID say example1@icloud.com exists on server and you know the password and its account credentials , however that is signed in the device iPhone .

If you don't remember the trusted number and yet it is verified in the account , visit your cellular service centre with personal identification proofs , the number can be obtained from them .

If the account is set with two factor authentication from iPhone .

Issue a sim on behalf of the same number and insert the sim Set up cellular service on iPhone - Apple Support

In a new iPhone that is purchased Turn on and set up iPhone - Apple Support

The Apple ID and password is active so is the 2FA active on the iCloud server , once a new trusted number is added the code will start appearing on the new trusted number , and the person can access the account .

See the article Get a verification code and sign in with two-factor authentication - Apple Support

Then access the account and remove an old inactive verified number from the account .

Go to your Apple ID account page and enter your Apple ID and password.

In the Security section, click Edit.

Click Add a Trusted Phone Number. 

To add a number, enter the phone number and verify it with a text. 

To remove a number, click cross sign next to the phone number you want to remove. 

Note : you don't need account recovery from the server as Apple ID and password are known to you How to use account recovery when you can’t reset your Apple ID password - Apple Support

Note :

( a ) provide credit card details that was added in the account to the apple support advisors .

( b ) if you have lost Apple ID password provide invoice copy of Mac to apple support advisors .

( c ) Contact apple support , they will send a link in mail account , click over the link after 24 hours to reset apple id password , however the link is valid for additional 3 hours .

( d ) Support pin is used by apple support advisors to verify the account when you knew apple id password Generate a temporary Support PIN - Apple Support

This is hard I had just went and updated my phone number as well