" It seems this question has come up on Houzz before but not many answers. "

Sketchup, Photoshop and or the like. Not inexpensive and they all have a learning curve. Easy does not exist for this.

I never use software for this because the issues with any are too much hassle. If you post a to scale floor plan here on graph paper show every window , doorway where those lead and every measuremnt clearly marked posted here in jpeg format in a comment DO NOT start another post . You will get help and many have gotten help before on this site so not sure what thta comment was about.

Floor planner dot com works pretty well and is free (or you can pay a modest amount per design for more options )