Because .7z is a generic compressed archive format, the exact contents can vary depending on where you downloaded it, but it most commonly contains:
: If it contains .bgl files, it is for MSFS or P3D . GrandCanyon.7z
: If you see this, the file is specifically for X-Plane . Because
: Documentation explaining how to install the scenery and any required dependencies (like library packages). How to open and view the content: GrandCanyon.7z
: Use a tool like 7-Zip (Windows) or Keka (Mac).