There is only one file type that uses the .LOOKLIBRARY extension:
Painter Looks Library
Library used by Corel Painter, a digital drawing application; contains a collection of media looks, which are a collection of images, such as neon streaks, vines, flowers, and branches, that can be added to the canvas; similar to .ABR Photoshop brushes.
A LOOKLIBRARY file can be created, imported, and exported in Painter. Selectand the Media Library panel will appear with tabs for Pattern, Gradient, Nozzle, Look, and Weave libraries. You can then choose to create, import, or export a library.
Updated: September 16, 2019