I put up some presets in a “Strings” thread that might be of use. Often, I run my guitar through a Whammy or H910/H949 algorithm upstream, so you may have to tweak them for bass input. There are adjustments built-in to the expression pedal settings.
The first two presets there are ‘ensemble’ effects. ‘Cello Bow Scrape’ could do the trick. Lower the RISE time for a faster attack. The HotSwitch setting really exaggerates the effect. The ‘Pizzicato String’ preset would be closer to a finger-plucked sound.