Unfortunately, we won't see him for a little while. Here's what we know so far.
Latest - 1.18 Out soon
Caves and Cliffs Part two finally launches in just a few days on November 30th.
When Will The Warden Release?
The Warden has been pushed back a few times to really give him the best entrance into the game.
For this reason, you won't see him for yourself until Minecraft 1.19 next year.
Where to Find The Warden in Minecraft
As it's dark and not well lit, the Warden and Sculk Sensor are based around not having a sense of sight.
Instead, they use your movements to monitor their surroundings. Moving over the sensor causes it to emit Redstone, moving near the Warden and causing it to kill you, almost instantly. Keep looking around the dark and you will eventually find the Warden.
How to Kill Them
The Warden isn't really intended to be killed. He deals huge damage and will take a long time to kill. As well as this, he doesn't seem to drop anything either. This being said, you can kill him, with a little bit of difficulty.
First, you will want to upgrade your gear to do much more damage. Having great armour isn't a must here as the top armour will only give you two hits from this behemoth. Instead, focus on his weak points. You can draw him away with a tactical snowball or arrow.
Move him into somewhere you can take advantage of his huge height and slow movement. Hide yourself away in a small space and attack him from distance slowly. It's cowardly but it works.