I want the box plot to show its maximum and minimum instead of IQR correspond to the box' edges in the graph.
So in the reference, it said

"By default, the whiskers correspond to the box' edges +/- 1.5 times the interquartile range (IQR = Q3-Q1), see "boxpoints" for other options."

But "boxpoints" did not talk about whiskers

boxpoints (enumerated: "all" | "outliers" | "suspectedoutliers" | False )
default: "outliers"
If "outliers", only the sample points lying outside the whiskers are shown If "suspectedoutliers", the outlier points are shown and points either less than 4"Q1-3"Q3 or greater than 4"Q3-3"Q1 are highlighted (see outliercolor) If "all", all sample points are shown If "False", only the box(es) are shown with no sample points