Every time a company launches a flagship with useful software additions, users start wondering whether these would make it to the previous gen that they already have in their hands. For the OnePlus 7 Pro, we recently learned that the screen recorder and Zen Mode would come to older models, but it turns out you don't need to wait to get the first one working. An APK of the 7 Pro's Screen Recorder was uploaded to APK Mirror and it works great on the 6T and older devices too, possibly.
After installing the app on your phone, you won't find it in the drawer. You need to open the Quick Settings toggles and look for Screen Recorder. Drag it up to your existing tiles, and this is how you'll be able to trigger the functionality.
Launch it, approve the permissions, and you'll get a floating menu on the screen with three buttons: record, settings, and exit. It doesn't show in any screenshot, but you can see it in the image at the top of the post.
The settings let you choose the resolution, bit rate, and orientation of the video, whether or not audio is recorded too, as well as enable touch markers to show where you're interacting with the screen, and pause recording when the screen is off.
The feature works very well on my 6T. I can tap the floating button to start recording, do whatever I want, control it there or from the notification, pause and resume, and then view the resulting video or delete it immediately. Here is a short GIF made from a video recorded with the app.
If you don't want to wait for OnePlus to roll out the feature to your device (which likely requires a new firmware), you can grab Screen Recorder from APK Mirror and give it a whirl. We haven't verified it on all older models, but odds are it works on the 6, 5T, and 5 just like the OnePlus team promised. While you're at it, you may want to give the new Gallery and Camera a go as well; I've tested them on my 6T and they brought a few interesting additions.
OnePlus has issued an official statement explaining that although this file works on older-gen devices, there are issues such as audio from games or music not playing. This is because the app isn't fully optimized yet for these models. Screen Recorder will make it into next week's open beta build for the 6/6T and should also come later to the 5/5T.