Apple first introduced the display tech in its Apple Watch. The upcoming iPhone 13 models are also tipped to come with LTPO display. Samsung has also used LTPO displays in the Galaxy Note 20 Ultra and Galaxy S21 Ultra. 
OnePlus 9 Pro leaked specifications
The 9 Pro is said to feature a 6.7-inch QHD+ display with a 3120 x 1440 resolution. The screen is curved and has a 120Hz refresh rate support. Other specifications include a Qualcomm Snapdragon 888 SoC, 12GB RAM and 256GB internal storage. The 9 Pro is tipped to come with 65W wired fast charging and 45W wireless charging. It will also support reverse wireless charging.
The 9 Pro will come with a quad-camera setup at the back. It two large sensors and two small sensors, which are speculated to be macro and depth lenses. The company has partnered with Hasselblad for the 9 Pro’s camera module.
The standard 9 is said to feature a triple-rear camera setup with a 50MP Ultra Vision camera. You can read about the leaked specifications of the device here.