Now, we have also known that the smartphone comes with OxygenOS which is the custom skin of Android that has been developed by OnePlus. The OxygenOS version of OnePlus 5T is OxygenOS 4.7.4 and this version of the OxygenOS is based on Android 7.1 Nougat. However, we have also seen that the latest version of Android has been released by Google earlier this year which goes by the name of Android 8.0 Oreo. Apart from that, Google recently released Android 8.1 Oreo as well which is the maintenance release on top of Android 8.0 Oreo which is expected to come to most of the devices.
Now, the official update from OnePlus to Android 8.1 Oreo is expected soon but we have now known that the Android 8.1 Oreo development for the OnePlus 5T has already started with the LineageOS 15.1 ROM making its way to Github. This means that the LineageOS 15.1 based on latest version of Android for the OnePlus 5T is going to release soon along with other devices so we should wait patiently for the update to come to the devices by next month which was the case this year as the LineageOS 14.1 was released in January 2017. Source: Github