Update the legend patch shape for all the classes in a feature class at the same time in ArcGIS Pro 3.5.x and earlier versions

Summary

In ArcGIS Pro 3.5.x and earlier versions, if there is a feature class symbolized with unique values, the shape of the legend patch cannot be changed at the same time for all the classes. It can be changed class by class, but this is not optimal if there are several classes. Starting at ArcGIS Pro 3.6, the legend patch shape can be changed for all the classes at the same time.

Procedure

In ArcGIS Pro 3.5.x or earlier

1. Open the Symbology pane for the layer to change the legend patch shape.
2. With Unique Values selected as the Primary symbology, choose a Field that has the same value for all the records., such as Shape_Length.

3. In the Classes section, change the legend patch symbol and choose the desired shape. If needed, hide <all other values> from the More drop-down list and uncheck Show all other values, as shown in the next two images.

4. For Field 1 choose the desired field to be symbolized.

The shape of the symbol is applied to all the classes. 

Alternatively, upgrade to ArcGIS Pro 3.6, where the legend patch shape can be changed for all the classes at the same time.