In desktop LR, you can hold down the Alt (Option) key while moving the Black or White Slider in the Develop module to set the Black Point or White Point. Is there an equivalent action in LR Mobile? What is it?
Slide the Black or White Slider in Lightroom mobile with two fingers instead of one.
That appears to do it, except it's hard to get two fingers there.
I find it easier to use the Middle and Ring finger than the Index/Middle.