ARCore, released last December, is a software development kit that helps developers create AR content for Android phones. Phones that support it can take advantage of dozens of Play Store apps, including IKEA Place, that lets you place AR furniture in your own home, and Google’s Just A Line, that lets you paint in the air.
The latest ARCore version (1.3) can be installed on the OnePlus 6 right now, but you can’t get it from the Google Play Store; the app is still showing as unsupported there, so you’ll need to seek out the APK file if you want to install it. This, according to XDA, works without issue though.