Can somebody please call tell me how to change my date

On your iPhone, iPad or iPod touch

1. Go to Settings > [your name].
2. Tap Name, Phone Numbers, Email. You may need to enter your Apple ID password.
3. Tap Change Birthday or Birthday.
4. Update your date of birth, then tap Done. If you want to change the date of birth for a child, find out what to do.

Update the date of birth associated with your Apple ID – Apple ...

It may sound weird and absurd but it is true and works...

When you find that the Date & Time feature is greyed out.

It is best to Set Screen Time Password Off and this will enable Set Automatic Date & Time

Watch this GIF below

Get help with the date and time on your iPhone, iPad, and iPod touch ...