There is so much at play here, pick up hotness, tone knob, bass pre amp.
As an example the Stellartone Tonestyler can add a bit of ‘grit’ to a tone. I use it with flats, clean for a nice slightly bitey tone for want of better words.
Another bass pick ups really likes flats, it just takes its response and I works better clean or dirty.
All variations on a theme