You can configure a report to let users adjust its grouping and stacking.
Configure alternative Group by and Stacked
by choices that users can select when viewing the chart. Additional
group bys can be added to any report that supports group bys (such as bar or pie)
and to list reports as columns. When you configure an additional group by to a bar
or horizontal bar, it is also added as an additional stack by. You can add variables
and variable groups as additional group bys.
Note: Available Stacked by fields are limited to catalog
variables, reference fields, choice lists, and boolean values. Date/time, integer,
long, string, and text fields cannot be used as stacked fields.