Reference designs are developed by semiconductors companies such as Texas Instruments, Analog Devices, or Microchip for designers. They are comparable to blueprints of an IC circuit in a specific application. The reference designs are developed to be copied by the designer, just like a recipe for today´s dinner including all information about ingredients, amounts, and preparation instructions. They usually include all the circuit information such as the schematics, Gerber files, BOM - but also the design performances under different test conditions.
Benefits of reference designs?

A reference design allows a designer to copy the IC design into their system without designing everything from scratch. Examples include the power supply section of a design or the LED controller.

It saves the customer time and resources by eliminating some designing and testing steps. In addition, most reference designs provide information about the circuit performances under different operating conditions. If the customer copies exactly the reference design, it ensures that the IC performs as expected.