There are two methods you can use to reduce the voltage level to work on the ADC Differential Pi.
You can use a voltage divider with the positive side going through the R1 resistor before connecting to the ADC + input and the negative connecting directly to the ADC - input. The R2 resistor connects between ADC + and ADC -. We have a calculator you can use to get the values for R1 and R2 based on your input voltage. https://www.abelectronics.co.uk/tools/resistor-voltage-divider
The second method is to use a fully-differential amplifier. An op-amp circuit is more complicated than a resistor divider but it does have the advantage of a higher impedance between the + and - inputs. Texas Instruments has a good article explaining how to use fully-differential amplifiers at https://www.ti.com/lit/an/sloa054e/sloa054e.pdf