bells and whistles

The phrase "bells and whistles" refers to additional, non-essential, and often decorative features or functionalities that are added to a product or project to make it more appealing, impressive, or advanced. These extra features are not necessary for the basic functionality but are added to enhance the overall experience or to attract attention. The term often suggests that these added features might be unnecessary or overly flashy, serving more as attractive embellishments rather than crucial elements.