If you click on the image below you'll find a self-explanatory list of what the features are, such "3-Way Calling" (allows 3-Way calling) and "Call Forwarding" (allows call forward). Your carrier will likely have the most accurate information about explaining what these features are.
Those are all of the features which are included in every plan by default . you could try to remove what you don't need but i don't think it makes sense since there are no extra fees.