The gesture is a new trend of the flagship devices. Android had gestures from a couple of years but after Apple introduced it, every android manufacturer wanted it in their device. Xiaomi & OnePlus already developed it for their device and the update is already live. If you are not one of them who received gestures in Android, You can use gestures by using one application.
Steps to Get OnePlus 6 Gestures in Any Android
#1. Download Navigation Gesture Application.
Download Navigation Gesture app from the play store or from the link given above. Give all the permission it asks and set it up. The application is free to use but if you want more features you can always buy it for $1.49 or Rs. 100
#2. Go to Setting & Gestures.
Just got to setting then gestures and set the gestures as you want. Make sure to enable Split Pill before you change the gestures function.
#3. All Set
Now Enjoy OnePlus 6 gestures in your Android device.