Yes, you can build a one-shot sniper loadout in Warzone 2 following the Season 3 update. However, only bolt action snipers equipped with Explosive rounds can kill with just one shot.
This means that there are currently only three sniper rifles in Warzone 2 with the ability to kill with just one headshot.
Additionally, each one of these requires players to unlock a different type of Explosive ammunition.
Here’s how to unlock every type of Explosive ammunition for one-shot snipers in Warzone 2, so you can take your pick of the three options!

Every Sniper Rifle That Can One Shot Kill in Warzone 2
The following sniper rifles can kill with just one headshot in Warzone 2 when you equip them with Explosive ammunition:
This is because they are the only bolt action sniper rifles in the game with an Explosive ammunition attachment.
Other bolt action snipers, such as the SP-X 80, don’t have an explosive ammunition attachment. This means that there is no way for them to kill with one headshot.
Additionally, the Signal 50 cannot kill with a single shot, even with Explosive ammunition, as it is not bolt action. However, this meta Warzone 2 Signal 50 build is still a decent option, thanks to its fast fire rate.

Will More Sniper Rifles Become One-Shot Kills in Warzone 2?
Warzone developer Raven Software has not revealed whether it plans to add more one-shot snipers to Warzone 2 yet.
If fans respond well to this sniper buff, Raven Software could consider adding the ability to kill in a single shot to more sniper rifles in the future.
This could be similar to Warzone 1, where lighter snipers and marksman rifles could one-shot headshot up to certain distances.
Implementing this change could be a good move from Raven as one-shot headhot snipers are one of the reasons why many players are playing Warzone Caldera again!