If like so many dealerships these days they have multiple sites selling multiple brands over several states. If you have a local contact in one state that is say a toyota dealership. One in another state that is a jeep dealership. Can your local contact help you with a used vehicle at the other site in another state?

Speaking from experience, most of the time no.
Usually the dealership that traded for it or purchased it will decide what they are willing to sell for.
So the dealership that's local to you will not have much say in the matter.

Sometimes, the large dealerships list all of their used cars on the website of each dealership.

It's been my (limited) experience that there's little negotiating on an internet advertised price on a used vehicle at a dealer.