After first launching its augmented reality 'Beauty Try-On' ad format with selected partners back in June, YouTube has this week announced that it's expanding the pool of brands who'll be able to access the function, while it's also adding the AR ads to its Masthead ad placement options, making them easier to find for users.

As you can see in this example from NARS, the next round of AR 'Try-On' advertisers will be able to push their ad to the front page, or improve discovery of the same via search.
Masthead ads appear above your recommended videos on the front page, so they'll be the first thing your target audience sees when they open up the app, while advertisers will also be able to place their AR Try-On ads in search results, and in the 'Up Next' section via the TrueView Discovery option.
The additional options will give the new AR try on format a lot more exposure, which should see also see them gain traction with brands who are looking for new ways to promote their beauty products.
YouTube's AR Try-On ads are displayed via split-screen, with the video playing on top, and your phone camera view opening at the bottom. You can then see what you, personally might look like wearing the make-up being discussed in the video.

Facebook introduced a similar AR-enabled option with selected advertisers last year, while just this month, Instagram has also begun a test of the same.
As AR tools continue to evolve, you can expect to see more brands looking for ways to integrate such functionality into their campaigns. At present, most of the AR-enabled ad offerings have focused on beauty products, but there'll likely be more ways to showcase different product ranges via creative, immersive tools as the options evolve.