How to aplly preset on a masking area

Hi there,

I usually use presets in Lightroom android. But not every part of picture or somepart I just want to set opacity of it few percents.

So, how could I do it? Because right now I have to use Photoshop in PC or Snapseed in Android (after I use preset in Lightroom, and then I use Snapseed to add orginal pic as 2nd layers and edit the opacity of it). It is too anoying and it seem not right for paid app like Lightroom.

Anyone have better solution for apply presets on masking area?