With selective adjustment, you can adjust part of an image without affecting the rest of the entire image.
1. Open the Selection panel
Tap the "Selection" button, and you will find a few selections that Polarr has automatically suggested. If you find "Sky", tap on “Sky”.
2. Adjust the sky
Now all the adjustments that are made here will only apply to the sky area of the photo.
3. Add layers to the sky
Tap on “Add Overlay” on the right hand side of the panel, and choose one of the layers you like.