Do you mean prior to med school like during undergrad or prior to med school like the summer before you start?
For the first, there's probably a research fair associated with your school. I got my undergrad research by cold-emailing a bunch of professors whose work I found interesting by looking at their faculty profile and one of them eventually took me. Sometimes professors will also ask for assistance from students that did really well in their classes.
I'll be doing research the summer prior to starting med school, but it's mainly to wrap up research I previously worked in. If I wasn't doing that, I probably would've cold-emailed faculty at the med school I'm planning on attending and seeing who is open and available to have a student come and help.