This app was mentioned in 3 comments, with an average of 4.67 upvotes
No need to find it in the store - when you redeem the code it will be installed on your device. And if you need the link to the store - here it is: https://play.google.com/store/apps/details?id=pl.ayground.coloringbook.plus
Looks like Coloring Expert+ by the same dev is also on sale for free.
Linnk shared wasn't working for me, searched and found in the app store.
https://play.google.com/store/apps/details?id=pl.ayground.coloringbook.plus