Currently, there are no third-party stat trackers in operation for Warzone 2. This is because stat trackers utilize a game’s Application Programming Interface (API) to track backend data for a given game, which is something that’s only possible once access is publically released by a developer. This has not yet occurred in the case of Warzone 2.
That doesn’t mean stat tracking won’t be possible in the future; it is expected that Infinity Ward/Activision will distribute the API in the near future. The first Warzone made it possible for APIs to be used to this end, and there were a number of excellent trackers.
Once the API is released, the best stat tracker in Warzone 2 is likely to be tracker.gg, which is a website that has a proven record of developing excellent software for stat tracking in the past. It is currently the number one best site for many other games, including the likes of Fortnite, Valorant, Apex Legends, and Destiny 2.