Call of Duty: Warzone 2 players discovered an XP exploit that allows them to max weapon levels almost instantly, but only until the game developers inevitably fix the hack. This is a desired weapon, a lot of money, and a lot of map racing, so while it’s not always easy to pull off, it seems to be able to put players in a prime position with regards to their weapon levels.
The cheat has already been shared a few times, but start by finding a weapon you want to level up. Sometimes it’s easier said than done in warzone 2, but it’s what you have to do first, unless you just want to level a random weapon, so get something cool that interests you.
Then start accumulating as much money as possible as fast as you can. Nothing too time consuming though, because it takes your time elsewhere to make this work, but take cash where you can find it (you were probably doing it anyway).
While you’re at it, keep an eye out for Safecracker Contracts scattered around the map. For whatever reason, these contracts seem to be running on an XP multiplier right now, which means you get extra XP for doing the second contract, more for the third, and so on. As war zone 2 grants players weapon XP for completing tasks like this, you’ll earn extra XP for completing multiple Safecracker Contracts. It is not clear if this multiplier is a bug or not, but if it is, it will probably be the first thing to be done once this exploit is resolved.
If you still need more XP after all that, some of the tutorials like the one above from IceManIsaac I recommend taking all the cash you earned and heading straight to a buy station to buy some armor plates. Those are the cheapest things you can get from the Buy Station, and buying things for some reason also earns you weapon XP, so more purchases means more XP. By the time you’ve done all of that, you’ll probably already have hit a weapon’s max XP level, or if not, you’ve probably gotten pretty close.