Content & Privacy Restrictions won't turn off on iPhone

I can only come up with 3 additional recommendations and would perform them in this order.

1.. Force Restart the iPhone

• Press and quickly release Volume Up
• Press and quickly release Volume Down
• Press and HOLD side button until the Apple logo appears. This can take up to 15 seconds while holding the side button before you will see the Apple logo and you have to ignore anything else on the screen during that time, including the prompt to Slide to Power Off. If you don't see the Apple logo while holding the side button, try again as it may take a couple of attempts to get the speed and sequence correct.

2.. Reset All Settings. This will not delete any data, but Settings will be reset a you will need to enter your Wifi password again when connecting for the first time.

Reset iPhone settings to their defaults - Apple Support

3.. If all else fails, I would suggest contacting Apple directly. Please update if a resolution has been found there. There is the typical phone/message tree to narrow down your issue, but you will get direct contact with Apple. When using the Online method, it narrows down to related Support Articles that may help, but on the bottom of the screen there is a link for More Options, where you will get a link to start a chat or phone number to call.

Contact Apple Support - Apple Support

Not sure what the link you provided has anything to do with your post. The post pertains to "Allowed Websites", not the issue you describe of not being able to turn off "Content & Privacy Restrictions".

Are you in the UK?

If you have not verified you are an adult as required in that region, there are going to be limits, such as Web Access, that you will not be able to turn off until you have completed the verification step.

Age requirements for managing an Apple Account in the UK - Apple Support

1. Is this your corporate/organisation/enterprise/School Management iPhone? Then please contact the system administrator of your corporate//organisation/enterprise/School Management
2. If it is your device, in that case, do you have any profile installed by your corporate/organisation/enterprise/School Management?
   1. Erase the profile added by you If you have installed a profile on your own --> Install or remove configuration profiles on iPhone - Apple ...
   2. Or please contact the system administrator of the organisation who provided the profile to you

A corporate profile installed on your iPhone could potentially be contributing to the inaccessibility of certain features. 

Here's why:

• Restrictions: Corporate profiles can have restrictions placed on apps and functionalities. These restrictions might be limiting some activity, causing it to be unresponsive or quit.
• Managed Apps: IT departments might deploy specific navigation apps through the profile, potentially blocking certain functions or features.
• Security Settings: Corporate profiles often have stricter security settings that could affect app or function behavior. This might be causing unexpected behavior of an App or functions.

Here's what you can do:

• Check with IT: The best course of action is to contact your IT department. They can explain the restrictions set by the corporate profile and see what is affected. They might be able to adjust settings or suggest alternative apps or features approved for corporate use.
• Look for App Conflicts: See if your IT department uses a different app through the corporate profile. Conflicting apps might cause crashes.

Additional points to consider:

• Even if the profile isn't directly affecting the function, it's still a good idea to check with IT. They might be aware of similar issues and have workarounds.
• While troubleshooting, make sure you prioritize safety. Don't fiddle with your phone. 

By working with IT and considering these possibilities, you can hopefully identify if the corporate profile is the culprit and find a solution that allows you to use the iPhone to your liking.

When you open Screen Time > Content & Privacy Restrictions and scan down to Allow Changes to, is everything marked Allow?

• It is correct that Apple may use a Credit card you have added to your Apple Account and I recall seeing that there is a permission prompt after the update asking if you want to allow Apple to use this for verification and that can be accepted or declined. I have also seen where this prompt will not come up even if a card is added. If you have a Credit Card in your Wallet, I have seen a previous post where changing that card to the Default Card allowed the verification to proceed.

Change or remove the payment cards that you use with Apple Pay - Apple Support

• Are you showing the correct Birthdate for your account where your age is 18+?

Update the birthday associated with an Apple Account - Apple Support

• Are you on iOS 26.5? If not, I would update first.
• When you go to Settings, do you have a message on top under your Apple Account with a Red exclamation point that says verification has not been performed?
• If no message in Settings, try looking for an app to download in the App Store that is rated for an adult to see if that will prompt the verification. One example is Claude by Anthropic, but that is not a recommendation to use the app and honestly I would delete it after download. The purpose is just to see if the age verification process will start.