If you enjoy simulating circuits, you’ve probably used LTSpice. The program has a lot of powerful features we tend to not use, including the ability to make custom components that are quite complex. To illustrate how it works, [asa pro] builds a potentiometer component that is not only a good illustration but also a useful component.
The component is, of course, just two resistors. However, using parameters, the component gets two values, a total resistance and a percentage. Then the actual resistance values adjust themselves.
To simplify making the symbol, the video shows how to read in an existing symbol — in this case a resistor — and then modify it to suit. Of course, at the end, you get to see how to actually apply the new component. Of course, the real value would be making even more complex components, but the potentiometer shows you all the techniques you need such as computing internal values and mapping pins to variables.
This is one of those things that isn’t all that hard, you just have to take the time to figure it out once. The video can help. If you need even more basic help, we have our own videos. Or check out some of the Circuit VR series.