I am looking at a 2016 Civic and the steering wheel cover looks a slightly different shade of grey than the rest of the interior. The seller says it is just normal wear and tear, but I am paranoid that the airbag might have deployed in a previous crash and was cheaply replaced. Is there a way to find out if the car has actually been in a major accident without taking the dashboard apart?

Mismatched interior parts are often a sign of repairs after a deployment. You should not take the risk without seeing the accident report, as insurance companies log airbag events when they process claims. I use a service that pulls these specific records for cheap so you don't have to guess. You can read here to see the full accident history and check if any safety systems were triggered in the past.