C:\Users\YourUserName\Documents\LightBurn\ArtLibrary
You can download pre-made libraries or individual .lbart files from several sources:
The most robust collection comes from the LightBurn Club subscription. For a monthly fee, you get access to a growing vault of hundreds of high-quality, categorized designs. Unlike random SVG downloads from the internet, these are tested for kerf, line thickness, and engrave-friendliness.