If I wanna patent my idea.. but there currently already have an app of it in a different state for which it's present, could I use and patent my idea that's similar to the existing one without getting sued?? Example: Uber and Lyft but in a state that doesn't provide those services (not technically Uber and Lyft)
I'm assuming what you mean by states are states within the United States. Patents have jurisdiction in a specific country not specific states. A US patent covers all of the United States. Even if there is no patent in your country for an existing product, the fact that it exists in public anywhere else means it constitutes prior art and would preclude it from being patented. Now if an app is sold in one state and there is no existing patent on it, you should be able to make your own version of that app without worrying about patent infringement. It wouldn't matter what state you are in. However, apps are also protected with copyright so you would have to avoid copyright infringement too. Copyright is off topic for this site.