Price: $9.99 Free (Free until October 31, 14:59 UTC)
Add F Texture Tools to your cart, then enter the coupon code FIMPOSSIBLE at checkout to get it for free.
https://assetstore.unity.com/packages/tools/utilities/f-texture-tools-274837
F Texture Tools is a pack of handy texture editing windows for use within the Unity Editor. With these tools, you can quickly adjust any image in the project to fit your needs.