Hmmm seems OnePlus doesn't have this option.
Have to tap the screen first or press the power button , damn troublesome.
On another note I managed to change to oxygenOS for my Shenzhen OnePlus 7T! Seriously Huawei xiaomi should all do the same and allow change to global Ron!
Just read from xda. Apparently they made this as not to put strain on front camera to always detect the face. Hence power button is to trigger front camera to perform face unlock.
Posted from PCWX using HD1900