The Samsung Galaxy Note 9 is one of the best smartphones of the year, with a pretty large display. It has a 6.4-inch display here, which is going to be great for using while in the car - to do things like navigate and stream music. But, in many States, you can get a ticket for holding your phone while driving. So you're going to want to pick up a car mount for your phone, so that you can still use it for Google Maps or Waze, or even streaming music in the car. Luckily, there are a ton of great mounts available, and all of the ones listed below are universal mounts. So they will work on the Galaxy Note 9, but also other smartphones - in case someone else drives your car from time to time and has a different smartphone.
One of the more popular car mounts on this list is the Spigen Kuel S40 Stealth Car Mount. This is because it doesn't use a magnet to hold your phone in place, and instead opens up to hold your phone in place. It's a pretty small and minimal car mount to use, especially since it does fold down pretty small when you aren't using the car mount. Definitely an important thing these days, as it won't get in the way of seeing the road. The only downside here is the fact that it only works in landscape mode and not portrait mode. Which likely isn't an issue for most people anyways.
These are all great car mounts for the Galaxy Note 9, and will all be great for driving with. Some of these use magnets, while others have adjustable arms to keep your phone in place. So they are going to do well at keeping your phone in place - and not letting it fall if you hit a pothole. If you haven't already bought your Galaxy Note 9, you can do so here.