If you'd like, I can give you specific steps for (like Mari or 3D Coat) or help you find licensing details for a specific project.
The by artist J. Roscinas is a collection of over 100 alpha textures designed for detailing stylized characters and assets. You can download this pack from professional marketplaces like ArtStation or Cubebrush . General Installation Guide
In the import dialog, change the "undefined" type to alpha and choose to import them to your current session , project , or library (shelf) for permanent access. 3. Blender