Слово settling означает комкование и скапливание пудры в мелких неровностях кожи, морщинках итп.

Вот примеры, из которых понятно, о чем речь:
____________________________
The powder blends perfectly with the complexion and thanks to the content of powdered minerals, it does not clog pores and does not settle in the wrinkles of the skin.
http://affectcosmetics.com/images/Affect_katalog_EN_2020.pdf

powder is the final step in any makeup routine. ... melt into the skin, so you don't have to worry about it caking or settling into fine lines.
www.byrdie.com › Makeup › Face

the formula is infused with amino acids and peptides that help hydrate skin and prevent the powder from settling into creases and dry patches.
https://www.bustle.com/p/the-4-best-setting-powders-for-dry-...
___________________________