Apple ID account problems

They would have to know the new email address to log in. Why not change the password as a precaution?

 Apple ID Password Change.   -   

 What to do after you change your Apple ID or password - Apple Support  -   I suggest doing this before you change your Apple ID or password.

Hi,

I would recommend changing your Apple ID password regardless if you have changed your Apple ID email or not.

To change your password, go to Settings > Name > Password & Security > Change Password.

Note: Once you change your password, select ‘Sign out’ on the pop-up you receive asking you if you want to sign out of other devices using your Apple ID.

• Change your Apple ID password

Once your Apple ID password has been changed, and you also have your trusted phone number set up within Settings > Name > Password & Security > Trusted Phone Number, your Apple ID account should be secure.

• Get a verification code and sign in with two-factor authentication
• If you think your Apple ID has been compromised

Hope this helps.