Assign Date range value to sql Declare

Hello,

im trying to assign start and end date value to a sql Declare stament.

I know i can do a slicer or a datarange filter but there is more complixed items to the query

does anyone know if this is possiable? below is a basic statment i testing with.

Thank you

Declare @startDate date = ?
Declare @endDate date = ?

Select

Count(SO_ID)

from Sales

where ORDER_DATE between @startDate and @endDate