Which one is it?
They make such a cute couple.

If I say,
They make a really cute couple.
They make a cute couple like that.

Question

Which one is it?
They make such a cute couple.

If I say,
They make a really cute couple.
They make a cute couple like that.

Answer

They make such a cute couple.
They make a really cute couple.
They’re a really cute couple.
They’re a really cute couple together.

Like that does not work in this context you need something to compare, to say why and how they are like a cute couple.

Like this:

“Walking hand in hand like that they make a cute couple”

Answer

They are a really cute couple.  (Though "make" is fine too... I think.)