My palette is small compared to most on this forum, but i've found
that some inks can truly modify line width,
and simply changing inks has made a significant difference for me with some nibs.
Here's my experience

To get a wider line:
Quink washable blue
Waterman blue black
Aurora black

To get a thinner line:
MB royal blue
MB bordeaux
Pelikan royal blue
Aurora blue

What's your experience?

Regards,
J