Can a default option value be automatically added to variants when an option is added to a product?

Shopify Partner
21 1 5

In the UI, when I add an option (i.e. color) with a value (i.e. white) to a product with variants, white will be added as a default option value for all variants.

Can this be done via API? Simply add an option and value and all variants will enherit?

My experience is that it forces me to set the option value for each variant or gives an error that a value  is missing and won't let me complete the call.