Sometimes you want to use a potentiometer to produce a voltage reference between two points on a range, for example if your supply voltage is 12v, you might want to use a potentiometer to give a reference between 3 and 10v.
Note that using a poteniometer as a voltage “regulator” isn’t a good idea, Ohm’s law will kick you in the nuts if you try to draw current from it, you need to buffer it with a voltage following op-amp for example.
Anyway, the appropriate way to do that is with a resistor on the top and bottom of the pot to “bias” it inside the range you need, but calculating those resistors is a bit of a pain, so I made this calculator for you. Just enter the Supply (Vin), the highest point the pot should give (VHigh) the lowest point (VLow), and the full resistance end to end of the potentiometer (RPot), the calculator will give you the Top and Bottom resistances, and the current through the divider network.