You do not grease bolts and expect an accurate torque reading.
Strictly speaking the applied torque is as “accurate” (or not) as the tool/measuring device used, I think you mean clamping force, and yes you will typical achieve higher clamping forces when using a lubricant to reduce thread friction.
So if you lubricate the threads you will apply significantly more clamping force, theoretically it could be twice as much. And as Jameso points out concentrating that clamping force over a reduced area will ultimately mean more load going into the steerer.
If possible use a full clamp stem, try not to exceed the specified torque (5 Nm?), I’d suggest using the bolts as they come, if they have blue Loctite pre-applied fine, if not fit them dry to maximise thread friction. If you don’t have a torque wrench, use the short end of a hex key to limit your mechanical advantage…