3 months after a BBL I have a flat spot, will this correct itself with squats and bridges? Please help (Photos)

That is a very common area for flattening due to normal anatomic pressure points.  Exercise is always good but in this case, it will not make much of a difference.  Additional fat transfer may help a little bit but you will have to mostly accept it as normal result especially in the face substantial fat transfer volume as in your case.