Not many are aware, but OnePlus phones ship with their own customized HydrogenOS for the Chinese market. What this does is it caters to the vast difference in style and culture between China and the rest of the world.
While the simplicity of an OxygenOS or a CyanogenMod ROM is probably what you’ve been looking for, it doesn’t hurt to use a more feature-rich software once in a while. This is what the HydrogenOS launcher does; it packs a lot more in it than say the OxygenOS launcher or a third-party launcher like Nova, etc.
If you’ve swayed towards the HydrogenOS launcher, but (i) don’t own a OnePlus phone so you can’t flash the entire OS or (ii) you don’t want to give up the other parts of OxygenOS just for the HydrogenOS launcher, you can proceed and install just the launcher via an .apk download on any Android phone!
Disclaimer: You’ll be installing the third party software at your own risk.
To do that, you simply need to head over to the XDA forums thread where a user ported the APK so it can work on non-HydrogenOS phones. Download the APK and install, and voilà! You have the HydrogenOS V4 launcher running on your Android phone.[Source, Via]