"Extra functionality" refers to additional features, abilities, or options that a product or system has beyond its basic or original function. It provides users with more capabilities or benefits beyond the core purpose of the item. Full definition
All in all, these software features provide a ton of extra functionality without being intrusive in any particular way, which is just the way it should be. (androidauthority.com)
It even supports add - ons for extra functionality. (howtogeek.com)
One of the key points of a dedicated reader is not to be distracted with too much extra functionality. (goodereader.com)