This question comes up from time to time. The short answer is , "Yes." We'll give you a formula for adding more cocoa.
But like life, it's not that simple. Cocoa contains starch so you have to reduce flour as you add cocoa or the recipe becomes too dry. (The formula tells you how.)
The cocoa has to be very good. It's hard to add too much good cocoa. It's a disaster to add too much bad.
As you add more cocoa, you need more sugar to temper the taste. That's mostly trial and error.
