the way I read the OP message description was from my old days in acad production and using the command LENGTHEN but to get the pline length on the command line.....
this is something that happens on my current job doing code nowadays - where there is in many cases ZERO explanations or does not lead to anything, no sketches, no drawings, so it takes more time to decipher the task....
a better description to the problem will lead to better responses - instead of end up wasting time.
my 0.2