AD5640: Increasing gain

Q

If I want an output from 0V to 3.3V (in a system with a 3.3V supply) can I put
a resistor between the output pin and the FB pin to increase the gain from 2 to
2.6?

A

This is not the best approach. The device is internally trimmed to comply with
specifications.
The device is designed for a 2.5V full scale output.
To increase this, an external amplifier should be used to increase the range.