There are plenty of things from the past that are absolutely real. We have tons of physical evidence for settlements all over the world throughout history. I’m sure there’s more yet to be discovered. But until we discover it, it’s just hearsay.

There may well have been a real place that inspired Plato’s mention if Atlantis, but only one. Not the many hundreds of possible locations suggested over the centuries. They can’t all be Atlantis, if any of them are.