Hi Namitha,
Please use the Analog Engineer's calculation for your reference calculation, see the attached link below. The transfer of the instrumentation amplifier (IA) is Vout = Gains*(Vin+ - Vin-) + Vref, where Vref is the Vout's offset voltage at nominal input. Since I do not have information about your input common mode voltage (green line in the graph), supply voltage, gain, I am unable to recommend the reference voltage.
Technically you may configure the Vref voltage anywhere within the supply voltage rails, which it will cover the Vout_min and Vout_max swing voltage range based on the above transfer function from the instrumentation amplifier's setting. If the IA's output is going to ADC, then you may require to configure the Vout within the range of ADC, which means that Vref may be configured near the mid rail of the ADC's sampling range.
BTW, it is more important to configure the IA's Vcm properly. If you are able to configure the Vcm in the middle of Vcm vs. Vout plot (green line of the image below), then you are able to maximize the Vout's swing for a given input voltage signal, gains and Vref. This will be easier to simulate it via Tina-TI, see the attached simulation.
https://www.ti.com/tool/ANALOG-ENGINEER-CALC
If you have additional questions, please let us know.
Best,
Raymond
