Hi Michele,
Welcome to the forum! Usually you do not need a large capacitor on the Trim pin, but the amount of filtering, either at the Trim pin or at Vout, will greatly depend on the precision of the ADC being used. Which ADC do you wish to use? What bandwidth and type of sensor is required?
There are also other factors that come into play as well. When adding another op amp stage you have the potential for adding noise and possibly offset error. Another area often overlooked is PCB layout. You can have a great schematic design that can be ruined by poor board layout. Also, the ability of the sensor input to be low noise is important.
Best regards,
Bob B