Is there a way to aggregate shipment forecast based on item attributes

Hi experts,

Is there away to have aggregate measure based on item attributes ?

For example 5 cars with different item code have the same attribute which is grey color. We want to see if we can generate forecast based on the grey color itself. For example total (SUM) shipment forecast of these 5 cars this year is 1000 but I have to calculate that manually checking each card then sum the values, how to show total/sum shipment forecast just for grey color attribute without checking every item ?