Apostrophes never form the plural except when you have a single letter like A and want to make it plural without having it look like "as." I got two A's and two B's. Now even years are written without apostrophes as there's no possible confusion: the 1960s. Of course, they aren't used to conjugate verbs: He know's* either.

What they're really for is taking the place of something missing of course: can't. And expressing the possessive.

Apostrophes have no sound so in "The Coles are here" and "The Coles' children are here, Coles and Coles' have the same sound.

On my mailbox I can write the Coles a plural name like the Romans, the Neanderthals, the Smiths of Connecticut. Plural names take THE!
Or perhaps the Coles'   as its OUR house.

Everyone named Cole tends to write on their mailbox "The Cole's", which is way wrong as the article "the" goes only with the plural. Einstein's theory; not the Einstein's theory.

The problem is that no one wants to write the Smiths or the Coles because people will say, "How are you Mr. Smiths? And you, Mr. Coles? So you get the mailboxes here:


I guess you can say
Jesus'(two syllables) name  and Jesus's name three.
Or Elvis' (two syllables) guitar or Elvis's guitar with three.
Perhaps you can decide which you like.

My ear says, however, that you can't say my boss' car. It must be two syllables so you can hear it: my boss's car.