[NOTE: enter your Android app URL (com.example.app) in the "notes" box on the cart page]
great for boosting overall ranking = increase visibility = increase organic installs/users
Check campaign delivery here: Google Play Console "first time installers" count should have increased by the bought qty of installs + if you have bought sufficient qty installs, then your app should rank higher in the app category.
NOTE: displayed downloads count on app's page will not increase with standard installs! For that you would need high retention installs.
You can estimate how many installs/day you need to reach a certain position, by checking how many installs your competitor in that position has per day.