Custom line end (Reverse arrow)

We need a reverse end arrow in our project.

Like this:

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I have created a custom line end and the arrow shape is three times larger
than the height of the bounding box.

In the project we usually use two different line widths: 0.72 pt and 4.08
pt. When using a standard arrow (type 13) online with width 4.08 the standard
end arrow is approx 3 times larger than the line width, while when using line
width 0.72 pt the end arrow height is approx 8 times higher than the line
width.

How can I make the custom end arrow be 8 times larger than line width when
it is 0.72 pt and 3 times larger when it is 4.08 pt?