Facebook is going to be trying out augmented reality ads. This, initially, seems to be based on a face altering app Facebook bought back in 2016, but otherwise there don't seem to be a lot of details available as of yet. You'll be able to try out sunglasses and try on different colours of lipstick.
Of course, this means you'll have to download and enable the app. And who knows what dangers lie in wait for you with apps?