Will turning off iCloud photos remove images from all devices?

My son (11) and wife share the same account. Every time a photo is taken they go on the others phone. I want to turn of iCloud Photos on my sons phone but he does not have enough space on the phone so says the photos will be removed.

My question is will they just be removed from my son’s phone which is ok or will they be removed from the cloud and my wife’s phone?

Tried for a while to look up this issue but think this will be quicker.

appreciate your time.

[Re-Titled by Moderator]