Highlights:

The OxygenOS 9.0.03 is being rolled out as an incremental upgrade meaning it will be rolled out to users in phases
The update brings the December 2018 security patch and makes system-level improvements
Features like Nightscape, Wi-Fi and Bluetooth have been improved

The 9.0.3 update makes improvements to the Wi-Fi and Bluetooth stability. This will likely help users connect to networks and devices better. The December 2018 security patch fixes a few vulnerabilities as well. The security patch also arrived for the Pixel and Nexus devices and the OnePlus 6T received it in December 2018.

The update also makes improvements to the Nightscape mode that the company introduced in the OnePlus 6T. It takes long exposure shots in low-light and stabilises them using AI. Right after the OnePlus 6T was announced, OnePlus also brought the feature over to the older OnePlus 6.

The update, as OnePlus confirmed, will be rolled out as an incremental update via OTA. “As always, this OTA will be incremental. The OTA will reach a small percentage of users today, and we’ll begin a broader rollout in a few days,” the company wrote in a forum post.

You can check for the update by heading to Settings → System → Software updates. You might want to backup your data before installing the update as a precaution.

OnePlus 6 receiving OxygenOS 903 update with December 2018 security patch\, bug fixes and improvements

OnePlus 6 receiving OxygenOS 9.0.3 update with December 2018 security patch, bug fixes and improvements

The update is being pushed out as an OTA (over the air) package which is usually rolled out in phases. The update makes some system-level improvements and makes the phone more secure.