Again, not possible. Live Photos requires, and has always required an iPhone 6s or later. This has never changed since Live Photos has introduced. It was introduced on the iPhone 6s and 6s Plus.
iPhone 6, and 6s, and iPhone 6 Plus and 6s Plus, look identical to each other. You cannot tell them apart by view.
I have a 6 plus and it has no live photos, it never has, because it does not support them. It can playback live photos if airdropped to it, but it cannot take them. Never has.
Whatever you are seeing, there is something amiss.
Go to Settings->General->About->Model and check what each iPhone that can take Live Photos around you has. You can then identify them exactly, and see for yourself.
There is no possible way an iPhone 5s, an iPhone 6 and an iPhone 6 Plus are taking Live Photos.
Take and edit Live Photos - Apple Support
Capture photos that come alive when you touch them. Then you can pick a different key photo, add a fun effect, edit your Live Photo, and share with your family and friends. All from your iPhone 6s and later.