erm - that’s a rabbit hole.
some preamps are aimed to sound a bit like a console transformer sound. (Caveman bp1, Jhs colourbox, api tranzformer, Hudson broadcast)
others give a valvey colouration to the sound. (Sushibox, Nobel preamp, shiftline and a million more)
Then there’s all sorts to give specific preamp crunchy sounds like bass amps.
but you’ll need to be more specific about what you’re after. For instance the Hudson broadcast and caveman stuff is both based loosely off studio preamp things - but very very different things!