Do you get charged for using a travel agent?

Excuse me, I was wondering, when it comes to using a travel agent to plan my next vacation, do I typically have to pay any additional fees or charges for their services? I've heard of some people opting for self-booking to avoid extra costs, but I'm not sure if that's the norm or not. Could you clarify whether or not using a travel agent typically incurs any additional expenses for the customer?