Summary symbol in legend

[GregSpontak]

A former coworker created the following in a legend using ArcGIS Pro (2.9 I think.)

I thought there would be some setting to summarize the layer's symbology - something to indicate that features are shown in unique values but without listing every value.  But I haven't been able to figure it out.  (And I don't have the map document to look in.)  Can anyone point me to how this was done?  I'm hoping I just haven't come up with the right terminology to search.

I'm sure I could convert the legend to graphics and create a patch, but I'm hoping that's not the only way to do this.

Thanks for any pointers!

[Robert_LeClair]

This kind of resembles bivariate colors symbology seen here in the ArcGIS Pro Help documentation.  

[GregSpontak · Accepted solution]

I heard back from my coworker and they don't recall making this.  So while I was hoping there was a setting to create this, I think it was just made as a graphic.

Thanks, Robert, for the suggestion.