How to unlock my son's iPhone without deleting the information.

If I access that page in the usual way the URL is

https://support.apple.com/en-gb/HT208510

as I'm in the UK. If I posted that then anyone, no matter where, would see the UK version of it.

However when I post these links I strip the country code off:

https://support.apple.com/HT208510

This (hopefully) results in people in other countries seeing the page for them, often in their own language. In this case the text is the same in the English versions such as for example

https://support.apple.com/en-sa/HT208510

or in translation

https://support.apple.com/ar-sa/HT208510

(I don't know which version a Saudi Arabia visitor would see by default, of course, since I can't check it).

I'm very sorry to hear of your loss. Please see How to request access to a deceased family member's Apple accounts - Apple Support

I too am sorry about your loss. Adding to what Roger Wilmut1 said, if you reside in the U.S., for example, then you will  need a court order instructing Apple to assist in the provision of access to a decedent’s information from the deceased person's accounts.

The requirement for a court order appears to apply in other countries, certainly the few I checked, as stated in paragraph 3 of the various countries' version of that page (my link will lead to the appropriate country for the OP).

Thanks Roger. Note that I said: "the U.S., for example .... " I am not sure what you mean by "as stated in paragraph 3 of the various countries' version of that page (my link will lead to the appropriate country for the OP)." Do you mean in the link you posted? Basically, do you have a link to the "various countries ... page ...."

Thanks Roger. I'll check all that out. I enjoy your posts. And, I hope all is well with you in the U.K. We now are missing out on another London stay we had booked. Be safe.