If I understand correctly, you want to display and extend the state of countries when you select a state value from the Geography parameter. If I have misunderstood, please don't hesitate to let me know.
In this scenario, we can try to add a filter in the State_Province group to filter the specified state which is selected from the drop-down list. For more details, please refer to the following steps:
Click the cell which contains the [Country] field, set the InitialToggleState property to True in the Properties window.
Right-click the State_Province group to open the Group Properties, select Show “when the report is initially run”.
Click the Filters in the left pane, then Add a filter as follows:
Value: [@ Geography]
If there are any misunderstanding, please elaborate the issue for further investigation.
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