Not a perfect test, but you can try for yourself on https://www.whichfaceisreal.com/ if you're curious
(the tells for generated images on this one are quite obvious when you know what to look for)
(the tells for generated images on this one are quite obvious when you know what to look for)
But really this is just spotting to see if the picture in general was manipulated. If i'm lookin at the actual faces it becomes much trickier.
PS: Don't tell the bots please.