How to re-set the size of the histogrm inset (sharpness) inside the reliability plot in the metplotpy ymal file

[BinbinZhou-NOAA]

I would like to reset the size of the histogrm inset (sharpness) inside the reliability plot in the ymal file of Metploypy.
But I can not find which parameter(s) in the ymal file can be adjusted for this. Currently the default size the histogram inset is too large for the reliability plot. I see the following text in the ymal file:
rely_event_hist: 'True'
or
inset_hist: 'True'

but no further sub-set parameters for them.

Binbin
NCEP/EMC