Set an outline offset value for features symbolized using Unique Values

Summary

When symbolizing using unique values in ArcMap, it may appear as though it is necessary to follow this workflow for each individual class after clicking Add all Values. However, the following workflow can be used to set the offset values, and other symbol properties, for all classes at once.

See the article: How To: Create enlarged outlines for polygons in ArcMap for more information about ArcMap workflow when using Single Symbol.

Procedure

1. Right-click the feature class in the Table of Contents and click the Symbology tab.
2. Choose Categories > Unique values.
3. Click Add Values.
4. Right-click one of the values and choose Properties for All Values.
5. Click the Edit symbol.
6. Click Outline.
7. Click the Edit Symbol.
8. Change to Cartographic Line and go to the Line Properties tab.
9. Set the offset value.
10. Click OK several times to return back to feature class properties. This changes all colors back to same value, but it does apply the offset
11. Click the drop-down for Value Field again to refresh the unique value symbology.
12. Click Add all Values. The symbology and offset now applies to all the classes

Note:
At the time of this publication, it is not possible to do this in ArcGIS Pro.

When working with one symbol at a time, any of its properties can be changed and even restructured by adding or removing components. When more than one symbol is selected, only the basic symbol properties can be changed, which vary based on symbol type, as follows:

• Color
• Outline Color
• Outline Width

See also: Symbolize feature layers

In addition, the following defects have been logged to address the equivalency issue between ArcMap and ArcGIS Pro: 

• BUG-000108431: When formatting all symbols, the buttons to modify symbol layers and symbol structure are missing from the Symbology format pane when the feature layer uses graduated colors with more than one class.
• BUG-000124648 : In ArcGIS Pro 2.4.1, symbol layer styles set for <all other values> are not applied to all unique value symbols when Add All Values is clicked through the Symbology pane.