Check the X-Plane.org Forum downloads section. Search for "787" under the "Heavy Jets" category.
Freeware versions usually feature a basic 3D cockpit and standard X-Plane systems. They won’t have the deep complexity of a $50 addon, but they are perfect for casual flying. 2. Freeware Alternatives: The Boeing 787-8 by "9100" boeing 787 x plane 11 full free download
These files often contain "cracks" (.exe or .dll files) that can trigger antivirus software or infect your PC. Check the X-Plane