Hi iPhoneSe21,
It sounds like you're wondering if you can see your iCloud messages via an online browser or download them. We're glad you've joined us in Apple Support Communities. We'll do all that we can to help you.
It looks like you've had the chance to review How to delete messages in iCloud. That's a great start, but we have some additional advice for you.
How these features work in iCloud depends on a number of factors, a key one being whether or not you had Messages in iCloud on or off. It also depends if you deleted the messages or not.
Since you came from a link about deleting messages, we will start there. If you have Use Messages in iCloud enabled and deleted them, then the messages will be deleted from all of your devices and not included in any backup. (See below in this post if this feature was off.)
If you had that feature on but did not delete any messages, Messages in iCloud are end-to-end encrypted, so you can't display or download them via iCloud.com. But good news, what you can do is look back at any device with Messages on them such as iCloud on your iPhone, iPad, iPod touch, Apple Watch, and Mac to see if you can see your older messages.
Another thing you can do is if you remember a keyword from that conversation is to search Messages. Go to the Messages App > Make sure you're on the page with all of your conversations > Pull down and a Search bar will appear at the top > Tap in the search field and type in your search term > Tap "See all" to see all the conversations with this search term.
If you had Messages in iCloud off, you can check and see if you had a backup before you deleted them. Follow the steps in Restore your iPhone, iPad, or iPod touch from a backup. Be aware that any information added to your device will be overwritten and revert to the date of the backup you use to restore. If you didn't have a backup, there's no way to recover these messages once you've deleted them.
You didn't mention being a Legacy Contact, but just in case that was set up prior to your son's passing here's some helpful information on that:
Take care.
