Sugar Cookie Mix In A Bag Can I Add A Little Cocoa Powder To A Sugar Cookie Mix To Get Choco Sugar Cookies?

Can I add a little cocoa powder to a sugar cookie mix to get choco sugar cookies? - sugar cookie mix in a bag

I have a mixture of sugar cookie that calls for 1 egg and 1 stick of butter. I cut out cookies. Can I have a small baking cocoa? How? Thank you!