It's a process
It's mainly your hands as a player
And the bass setup and strings.
It comes with practice.
Also not falling into a trap and thinking a million bass guitar mods and fancy amps or compressor fixes everything
Note defintion comes from your hands. The way you play the strings.
I learned note definition with very cheap standard basses
I'd say playing unplugged and listen to the bass body and strings. And spend time learning how your hands can get clarity.
Find tone by plucking near the neck, in the pickup area and toward the bridge. Your note attack will change cause tension is different in all those spots.
You don't have to play mind melting amazing notes. Heck, pluck one note till you get a feel for the bass.
Playing unplugged you hear the body and the frets on the neck. Don't be clouded by amp settings or setup.
Just feel the bass.
Once your in touch with your instrument.
You'll understand why some guys want
" flat" EQ. They just want the sound of the bass and tone is in the hands.
Your fingers will hurt and will be sore.
It's a process
Otherwise I've always liked sealed cabinets
And once in touch with my bass. I tend to enjoy the feel and accuracy of sealed cabs and very very minimal EQ