That is not how it works.But still, protection is needed and Ohm's law still cannot be beaten. With a current limit of 500mA, we will have 12 (24 * 0.5) watts of power on the key element, in which case each of the discrete outputs will have to be equipped with a boxed processor heatsink)
When the current limiting electronics kicks in, it reduces the voltage not by increasing the resistance but by quickly chopping input voltage, and probably with some dampening to not generate a lot of noise. In this way there is no excessively high heat dissipation in the module.