devices also you may check it and give reply here in the comment.We have already posted about on how to enable Face detection in Moto E 1st gen and 2nd gen also without root.You can check below link for reference.
#How to Enable Face Detection in any Motorola Phone
1.First download modified Moto Camera.apk from below link
►MotoCamera + (Don’t make mirror of this link)
2.Now install this moto camera + app and open it.Swipe left on the camera to open setting you will see a small picture of bud on the right bottom of the screen as in below picture.
3.Now there will we setting window when u click on bud then swipe left and on the top there will be face detection menu just click to On.Few setting to be done that don’t ON app info and stowed sensor.