Oneplus has just announced a new OxygenOS 4.5.0 will be coming to the Oneplus 3 and 3T over time which will bring a lot of features we have seen in the new Oneplus 5 to these older devices. The update will be rolling out incrementally over the next few days, so will just be a matter of time before we start seeing it on the devices here.
Oneplus has confirmed that features like Lift Up Display, Gaming Do Not Disturb mode, network speed in status bar and schedule night mode will be coming to the older devices in the coming update. According to Android Police, the size of this new update will only be 197MB which is considered pretty small for all the new features that will be coming in. The biggest visual of these changes is the Oneplus Slate font which was previously only available on the Oneplus 5, this brings the fonts that are in the new phone to these older phones.
However, this update is only a visual update as it will not bring about the new security update or Android 8.0, but it is still very nice to see the company supporting older devices even if the devices are over a year old and bringing the experience of their new device to its older devices