The default motion mode is determined by the general tab of the configuration dialog. Exact Stop (G61) or Constant Velocity (G64), CV for short. G64 is the semi-equivalent of you motion smoothing. Most of the time, G64 (CV) is the default motion mode. G64 it is primarily characterized by the acceleration capabilities of your machine. The higher the accel settings/capabilities, the closer CV cuts to the true path. There is a way to tailor the CV settings by angle. But there isn't a way to blend with a number in a range like your G5 command.
Steve