Horizon elevation

Can you please clarify. If the horizon elevation was say 15 metres above sea level, if I increase elevation in Starrynight Pro 8 is this the same, as I thought it would increase my elevation, from my location, and not the horizon, or is it the same? I need to know please to accurately measure sunrise azimuth at varying elevated horizon locations? I am only asking this, as I imagine the program is not clever enough to be able to know and calculate the ACTUAL real horizon level that would be apparent, based on the actual longitude/latitude of the real location?Thankyou 😊