I remember hearing this many, many years ago, then forgot about it. I was reading a thread about actors being tiny in real life and how the camera adds visual weight to them, and that this is an actual thing.
I must admit I do look larger in photo's but thought this was the crappy quality of iphone lenses. I know from having studied photography in the past that even a 50mm lens isn't kind to the human figure, so over 85mm would be more natural/flattering. And obviously the iphone really does distort (you will be happy to hear!).
I have only met one actor in recent years and she looked very similar to her on screen, slim self.
But is it a thing in general? I never notice if other people look bigger in photo's as only really notice myself, lol, in terms of weight.