ArcGIS Pro 3.4 API Reference Guide
ArcGIS.Desktop.Mapping Namespace / UniqueValueRendererDefinition Class / DefaultSymbol Property
Version

DefaultSymbol Property (UniqueValueRendererDefinition)
Gets or sets a symbol that will be used to draw features whose values are not found in values list.
Syntax
public CIMSymbolReference DefaultSymbol {get; set;}
Remarks
You should use this when there are more unique values that what you set as ValuesLimit.
Note, this is only applicable when UseDefaultSymbol is set to true.
Requirements

Target Platforms: Windows 11, Windows 10

ArcGIS Pro version: 3 or higher.
See Also