The context for my question: Linux Mint 21 Cinnamon, emacs version 28.1.2 compiled from source by myself.
See the image to know what I am speaking about:
being apparently not alone with such kind of question, as there is another not yet answered question here close related to this one (but NOT a duplicate, because it asks for something else).
I have already added the lines:
(setq-default fill-column 73)
(setq-default display-fill-column-indicator-column 73)
(setq-default whitespace-line-column 73)
into .emacs file but it does not have any effect as emacs is still using 80 as the column number to start coloring the line, not 73.
UPDATE: I have already checked out the solutions provided in the answers to the question: How can I get a ruler at column 80? as you can see from what I have already in my .emacs file.
And NO, I don't want a visible RULER at a given position. I want to keep the behavior of coloring the tail part exceeding the maximum specified line length as you can see in provided image.
There is a reason why I have decided to provide an image in my question and the reason is to show clearly what I want to achieve. So you can see in the image that I am not seeking a ruler shown at a given column ... AND you can see from what I have shown to have in my .emacs file that I have already tried the solutions provided in the suggested other question without success.