Yes, it can. To do this, ensure that there are no downsampling options enabled in the unit, and that the volume control is set to 0.0dB.
Both S/PDIF and AES are 24-bit interfaces. As such, a 16-bit signal has to be sent with padding. If done correctly with no volume control, the DAC should show 16-bit. If any volume control is applied (the unit is set to -1.0dB), the DAC will show 24-bit.