OnePlus Switch is an app that lets people quickly migrate their stuff from an old phone to a OnePlus device. It comes standard on OP phones now, going back to the 3/3T. The app just got updated to v1.2, addressing a few issues and improving what can be transferred.
App data can now be sent together with installed applications.
Here's the changelog:
- Support application data, download and office files transfer;
- Optimize UI for improving user experience
- Solve the transfer data repeat problem
- Add “System stability improvement program”
Switch can now move app data, downloads, and office files to your new OnePlus phone. Though it's news to me, it's good to see that OP addressed the "transfer data repeat" problem. Otherwise, you can join the new System Stability Improvement Program if you so choose, though that doesn't seem all that exciting, to be honest — still, you have that option available to you.
If the Play Store update hasn't hit your phone yet, you can grab it from APK Mirror.