change the date in ssis package for XML file

You can use a derived column transformation :

(DT_DBTIMESTAMP)DATEADD("day", -2, GETDATE())

 

If you need different dates for different rows, you can use conditional expressions based on existing logic. If you need a rolling two-day period, you can apply:

(DT_DBTIMESTAMP)DATEADD("day", -1, GETDATE()) -- Yesterday
(DT_DBTIMESTAMP)DATEADD("day", -2, GETDATE()) -- Two days ago

 

If you are comfortable with C# you can use a script task :

public override void Input0_ProcessInputRow(Input0Buffer Row)
{
    if (!Row.MyDateColumn_IsNull) // Replace with actual column name
    {
        Row.MyDateColumn = DateTime.Now.AddDays(-2); // Set to two days ago
    }
}