Is there such a POV as First Person Third?

No. It is either First Person OR Third Person.

Stories with First Person Point of View are stories where the main character tells the story. "I saw the body in the alley."

Stories with Third Person POV are stories where the author tells the story about the main character. "He saw the body in the alley." The author is not involved as an actor in the story. [A rum thought occurred to me that the author tells us his own slant on the story. What if another author had written a version of Romeo & Juliet, making Tybalt his hero? It would still be told in Third Person point of view; but from a different perspective.]

Sometimes a secondary character tells the story. Dr. Watson acts as both narrator / writer of the stories of Sherlock Holmes, but he is also writing down his own experiences. So, he writes in First Person Point of View when he is telling us what happened to himself. "Killer Evans shot me." He also writes in First Person point of view when he is telling us what he sees Holmes doing. "Holmes grappled with the cab driver." Also when Holmes finally sits down with him and explains his "process of deduction". What Holmes did or said is filtered to us through Dr. Watson, so he is the viewpoint character.

How would that be possible? It can't be told in the first person and the third person at the same time. Do you ever read any books??

Describing yourself describing something? Sounds dumb.

That makes no sense.

Describing yourself describing something? Sounds dumb.