Appel has had a People & Pets category in the Photos app for a very long time; that's not what is new with the redesign the app has undergone in iOS 18. But there's something new for People & Pets that I, for one, am really happy about. It's now easier to find the option to change the Key Photo for anyone in the People & Pets section.
The People & Pets section has some sort of special talent to always curate the worst photos and set them as Key Photos. Earlier, many people couldn't find the option to change