This webstory will help you in understanding how you can change the email passwords on iPhone.
Apple provides you with the feature of adding multiple emails with different service providers.
There are multiple emails supported like: Gmail, Outlook, Yahoo ,etc.
Go to the settings app of the iPhone and open the "Passwords" tab.
Give Face ID or Touch ID. After authorization, click on the change passwords tab to proceed in changing password.
Select the email service provider that you use for example Gmail. Then open the service provider settings.
After opening it, enter your old password and then your new password. This would successfully change your password.
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