My Cambridge dictionary gives such a definition and one of examples: turn out = to happen in a particular way or to have a particular result, especially an unexpected one 2) to be known or discovered finally and surprisinglyLiliana, I think that "it turned out that" might sound a bit awkward to native's ears. I was taught that one can say "turns out to be, as it turns out, he/she/it turned out to..." but rarely "turned out that". It might be considered a loan-translation, but I can be wrong.
It might be permissible but frowned upon by native speakers, which is often the case with some expressions. I remember some native speaker pointing out that "It turns out that" sounds awkward to him. I'd have to flick through my posts but it might not be worth it as it seems to be just some individual peculiarity - having looked it up, it seems to be perfectly fine. But if I were to choose from these two versions:guniang said:It turns out that she had known him when they were children
So, apparently, 'turn out that' is acceptable.