Please add the Aggregation options to the Symbology window. They are currently (ArcGIS Pro 3.1.2) only on the Ribbon.
The Symbology window seems like the more obvious place where someone would look for these options.
After you have selected the option, you still have to go to the Symbology window anyway to work on the symbols.
Here are a couple of places I think you could put it. The Primary Symbology drop-down list is already very long, maybe the suggestion in the second image is not the best choice.


Thanks!