Hi Francis
I hope you are well. I just use FaceApp. I have the paid version, which has a lot more filters than the free one. It's not just about smiles - you can do much more, from hairstyles and colours to make-up and age. It's quite a nifty litttle editing suite.
It does work better with some faces than with others.
Any more questions, just ask.
Cheers
PD