Is It Possible to Widen the Mid-face with Cheek Implants ?

What you are referring to are cheek implants that produce more width or zygomatic arch expansion rather than forward projection. That can be done by proper selection of cheek implant style and getting them placed far enough out or back onto the zygomatic arch area.

Yes- Cheek implants can be selected to offer widening of the mid-face in the properly selected patients.  Dr Harrell

 IMHO the aesthetics of facial beauty are well defined as are the ideal shape and size of the cheeks in both men and women under "The Palmer Code".  The cheeks when properly shaped, can convert an elongated "rectangular" face into a feminine "heart" shaped or a more angular, "masculine" shaped face in men.  

 The outer segment, of the cheeks, should not be augmented as this gives the face an un-natural wide, broad and unattractive appearing face.  Understanding and following the proper aesthetics of facial beauty for the creation of a naturally more attractive face is the main selection criteria for choosing your plastic and cosmetic surgeon IMO.