Does this bass effect exist ?!

I am looking for a bass effect pedal for live work - which I can use to
enhance the bass sound to make it sound more like a 6 string electric
guitar playing a distorted chord - or at least something that can
really pad out the sound when required
Basically we're a 3 piece band (bass. guitar)and want the option
for the bass to fill out certain areas of a song - like choruses or
under a guitar solo - giving more depth to our sound

I think It's called an 8 string bass. You can pick one up fairly cheaply
these days. If you REALLY want it fat. get a 12 string. That and a little
overdrive should do ya.
Conservatives are not necessarily stupid.
but most stupid people are conservatives."
- John Stuart Mill

Does exactly what you want.
which i have done in the past and it sounds really good. great for unison
rage against the machine type parts too.