My child’s iPhone time zone is wrong

If you have forgotten your Screen Time passcode. There are two options.

If you are unable to reset the Screen Time passcode from this-> link then, you will need a computer for option 2. If you don't have one, borrow one from a friend.

Option 1

Use this link to reset your passcode If you forgot your Screen Time passcode - Apple Support

Option 2

Forgot? Click below to reset…

Click->If you forgot the passcode for your iPhone, iPad, or iPod touch, or your ...

If you have chosen option 2 then regarding your data, If…

1. You have an iCloud or iTunes backup, I am sorry there is no use of a backup because if you restore from your backup your Screen Time Passcode will be back. 
2. You have synced your data to iCloud, then what you will get back is what you have synced to iCloud and uploaded to iCloud Drive; the information that is synced and stored in iCloud are, Contacts, Calendars, Bookmarks, Mail, Notes, Voice Memos, shared photos, iCloud Photos*, Health data, call history, and files you store in iCloud Drive. (*-If you had turned on iCloud Photos, your content is automatically stored in iCloud.)
3. You have imported your Photos & Videos to Mac/PC then they are safely residing there
4. You have uploaded some of it Cloud Drives using the Files app (iCloud Drive, Google Drive, OneDrive, DropBox, Flickr, box, AmazonDrive, Adobe Creative Cloud etc)
5. If you have not imported nor you have synced or uploaded your data to cloud drives prior to forgetting the Screen Time passcode then I am sorry, all your data is lost.

On your iPhone or iPad

Make sure you have the latest version of iOS or iPadOS. Turn on Set Automatically in Settings > General > Date & Time. This sets your date and time automatically based on your time zone.

If you can't change the time or time zone on your Apple device

Re: “… this needs to be adjusted on my son’s phone? … “

Yes, that is correct.

First, your child’s phone must be a “properly” setup Child’s AppleID with his/her accurate DOB.

This can ONLY be done by the “Family Organizer.

Set up Family Sharing - Apple Support

Create an Apple ID for your child - Apple Support

Then:

On your child’s phone, go to Screen Time.

At setup select “This is a Child’s Phone.”

(This allows you to add your OWN “special” passcode unknown to anyone else. You should also link it to your AppleID to aid in any future “recovery” efforts.

Then … turn on the necessary “Controls”. Anything you change here can’t be “unchanged” w/o your special passscode.

Use parental controls on your child's iPhone, iPad, and iPod touch - Apple Support

The ones you SHOULD restrict are in “Other Features”

Account Changes: This will prevent your child from signing out of his account and into “somebody elses”. (another common “end run” methodology )

It ALSO prevents him from changing the time or Time Zone.

Passcode Changes: This restricts him from changing his passcode — which otherwise can be used to lock his parents out of his phone.

Cellular Data Changes: Prevents child from playing “musical phone numbers” with other SIMs they might obtain.

This change can't be done remotely.

FYI, time zone shifting is generally a way to “end-run” around ScreenTime controls.

You can “lock it down” in the “Parental” ScreenTime set on his/her phone.

Hello ~ Excellent! 👍

~Katana-San~

Thank you.