Define "Near"? 
My DJI, and I expect most of the drones they make determine GL at the point of powering on the drone.  If your drone is turned on at the top of a hill, that sets the DJI limit imposed for the rest of the flight. The power-on altitude is determined by barometric pressure at the time and place. If you are legally limited to 400' AGL you can easily become illegal if you launch from a hill top and fly over a valley and likewise, if you launch from a valley, you may find yourself software limited in getting over a big enough hill, legal or not.
I have heard of some who have built an enclosure in which you place the drone to be powered on. If you pull a vacuum in said box, while powering on, your software imposed ceiling will be increased proportional to the vacuum pulled.