What is the method to include a linear trend line according to boxplot() function?

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The boxplot() function does not include a method to add a linear trend line. The function is intended to create a visual representation of the distribution of a dataset through a box and whisker plot.

If you wish to add a linear trend line, you may want to use a different plotting function, such as plot() or lmplot(), which provide options to add trend lines or regression models to a plot.