Standard ways to make a variable low pass filter
You can use a digi-pot to make the resistor variable. Then select multiple capacitors that have values that define the filter ranges that work with the resistance range of the digi-pot. Use an analogue mux chip to select which capacitor is switched into the filter circuit at any given time.

Deploy a microcontroller to control the pot and mux. The MCU can also support the user interface of your choice.