Heater isn't hot enough in my car, is there a way to make the heater better?

I drive a 1998 Ford Taurus Wagon, the heater on it is alright but when it's 10 degrees outside it kinda sucks.
Is there an actual way to make your heater hotter?

If the thermostat is stuck open or opens at too low of temperature, that will cause a problem with low temperature air coming from the ducts. With that old of a vehicle, the door and window seals are probably leaking and allowing too much heat out (cold air in).

Check that the thermostat is functioning properly, the coolant flow through the heater core is not blocked and that the fresh air flaps closely fully so the colder ambient air does not mix with the air flowing through the core.