Create tag or filter based on contents of product description

[miles]

A product has 2 options but the SKU is the same for both. The SKU has to be the same because at my marketplace, the 2 options need to combine counts for a quantity discount.  If the SKUs are different, they won't combine.

I would like to treat the 2 options differently. This requires a filter or automation rule of the form, for example:

Order description    Contains     [option text]

That would allow me to tag the options separately and create different shipping specs for each.

Thanks.