How to change the email password in iOS 18.0?

this does not answer the question, which is: how to change the EMAIL password.

the above describes how to change ones APPLE ID/ACCOUNT password, which is not the same...

Change your Apple Account password - Apple Support

This is how you change your Apple ID password on your iPhone, iPad, iPod touch, or Apple Watch:

1. Tap Settings > your name > Password & Security.

2. Tap Change Password.

3. Enter your current password or device passcode, then enter a new password and confirm the new password.

Forgot your password? Go to --> If you forgot your Apple Account password - Apple Support

4. Tap Change or Change Password.

● If an app or feature on your device is not working, not appearing, or is restricted (grayed out), a frequent reason is it may have been disabled using Screen Time, or by an IT administrator if you are using a device owned by an employer or educational institution.

- Read this support article If your Apple ID or other options are greyed out in Settings —> If your Apple ID is greyed out in Settings - Apple Support

Tap Settings > Screen Time > Content & Privacy > scroll to Allow Changes and turn on.

- If the device is managed (Settings > General > VPN & Device Management), contact the IT department that is doing the managing.