Recovering photos from a potentially damaged iPhone using the same iCloud account

All of the previous comments are true, and sad. But you don't say what your son did with his two phones and his iCloud Account. If he used iCloud Photos, then the pictures would still be in his account at iCloud.com, and you can go there and see them and download them. If he didn't use iCloud Photos, but he had on his phone turned on Settings>Apple ID>iCloud Backup, then that backup may have his stuff. In that case you could restore them to another phone.

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support 

This is what you do when you buy a new phone, so this backup, if you have it, requires you to erase everything on your phone and replace it with the backup.

tah178 wrote:

So even if he’s logged in on his other device at home everything is gone?

Unless the photos are already stored in iCloud Photos, or were stored or backed up elsewhere prior to the damage, the contents of a damaged device are unavailable.

As too many of us eventually get to learn, backups are the only way to mark data as being valuable.

You can certainly have Apple Support review the device, but they usually provide a refurb and not a component-level repair. Or will usually suggest replacement for older iPhone models.

Backups have to occur before the loss, theft, damage, dunking, fire, failure, whatever.

Most of us unfortunately learn about the need for backups by losing our data; the hard way.

If the photos are not already in iCloud Photos, or backed up elsewhere, then they’re likely gone.

tah178 wrote:

He has 2 iPhones with the same iCloud. He left one at home and he brought his 11 on vacation. Water leaked into the water pouch and now his screen is black. So he’ll be using the 12 pro max when he gets back home

How many phones are associated with the Apple Account is not relevant to this case.

What is relevant are what backups exist, what previous copies of files or photos exist elsewhere, and what iCloud services were in use.

Maybe the phone can be dried out, and gotten working enough to get the data off it. Maybe not.

Separate from whether the phone can regain function after drying, water damage is not considered to be repairable, as it tends to lead to corrosion and other issues.

And as a related question, Is the other phone now being backed up? If not, start there.

tah178 wrote: … The other phone is home so I won’t be able to back it up til Saturday

Again, if he's using iCloud Photos, then his pictures will already be available on his 12 with no extra steps needed. iCloud is all about having data on multiple devices-- that's why having two phones could be important. Also, if he used iCloud Backup (a separate iCloud service,) he can restore the 11's data to the 12 (though he would have to erase the 12 first.) Unfortunately, if he didn't use iCloud Backup or iCloud Photos, then he's stuck crossing his fingers and hoping the 11 dries out without damage.

If your son did not back up his phone, and his phone is not operating normally at this time, it is too late to back up the "fried" phone.