Revit can automatically apply a line style to silhouette edges. Silhouette edges are view-specific.
After you have applied silhouette edges to the model, there may be edges you do not want to display in silhouette. You can remove these lines as necessary.
To apply a line style to a silhouette edge:
Silhouette edges are not available for Wireframe or Shaded model graphic styles.
To remove a line style from a silhouette edge:
For more information about the Linework tool, see Changing the Line Style of Elements.