The revised cone fastening system works with an expansion cylinder: when the lower screw is tightened, the cylinder expands and presses firmly against the inside wall of the fork steerer. Even if the cone looks too small at first glance, it reliably adapts as it is tightened.
After inserting it, screw the cone firmly into place until you hear a cracking sound. Then continue turning until the cone is securely and firmly seated in the fork steerer.
Here is a helpful animation showing how it works: