At this point we already know that the patents registered by the Cupertino company may or may not reach the devices, but what these patents show in most cases is what is really interesting. In this case it is a patent that is related to the optical sensors used in the Apple Watch and is that They are somewhat more curved or ergonomic to the shape of our wrist.
And yes, when we look at the bottom of the current Apple Watch and all Apple smart watch models, we realize that they have improved ergonomics but in no case can we say that they have a "normal" watch design as we know them.
Many watches are flat but smart watches and in this case Apple's is curved outward, we have a belly. This could be improved with the new sensors that Apple is patenting since they would allow modify the current design of the lower part of the clock so that they are slightly less thick.
There are really many components that have to be retouched in order to "slim down" the device and in the patent obtained we only talk about a curved sensor like the one you can see in the image above. In short, it is about perfecting the design of the current model to make it much thinner, but this task is not easy and the Series 5 has the same thickness as the Series 4 although it is true that it is somewhat less in thickness than the series 3. Every year a few millimeters are gained and the sensors and internals of the watch have a lot to do with this battle of final thickness. We will see what happens in the future with the following generations of Apple Watch, for now it seems that the Series 6 will continue with the same design as the current model, the Series 5.