Yes you can buy car parts from a car dealership.
Dealerships not only work on cars and vehicles but they also sell car parts to the public although the car parts that dealerships sell to you are gonna be more expensive than other places.
Some car parts can only be bought at dealerships.
For example I had a Ford Taurus car that needed a couple of brake lines for the rear that were metal and they were just small brake lines.
I looked all over for those brake lines and finally went to a dealership and yes they had them.
But those little brake lines cost me $40.00 each for some little pieces of metal.
But I needed them and so I bought them.
In the garage part of the dealership there will usually be a parts counter and all you have to do is ask the dealership about parts and they will take you to where you need to go.