Since the default setting in model space for LTscale is one (1), you will need to change it to a scale factor value. To calculate the scale factor value, you must know the scale that you will use to plat you drawing. Assume the scale of the drawing is 1/2"=1', the scale factor value is 12"(=1')/ (1/2")=24. If the drawing scale is 1"=50', sfv = 600"(=50')/1"=600.
This method works for about 80% of all drawings if done at the start of new drawings. If this does not work you will need to change the SFV of that line under the property of that line.
Since drawings may be complex with different scales when plotted, if changing to a new SFV for that line does not work you may want to go in the opposite direction for a value and that is selecting a fractional value such as .5,.01,.005 or others until you get the result you want.
When you are in layout and open a viewport, you will see that line as a solid, therefore, type psltscale and change the default value of one to zero, then type regen but before you do make sure that the bottom tab is change to model space while you are still in layout.