It couldn’t hurt. 
Are you doing structured workouts in ERG mode on Zwift? After you do the auto-spindown calibration, it may be worthwhile to do an FTP test in Zwift. Since last December, we rolled out a new FTP test in the Watopia expansion called The Grade. If you ride the Elevation Evaluation route and maintain a full effort until you reach the top - it will tell you if your FTP has increased.
What are you using to measure your power outdoors? Is it a crank or pedal based power meter reading to a GPS head unit, and if so, which make / model?
There will always be a discrepancy comparing to power read at the pedals vs at the rear axle. This is due to power losses in the chain - typically up to ~5% loss. That said - if your pedal power meter says 230w, a 5% loss means ~218 watts indoors, and that doesn’t seem enough to account for your discrepancy.
There are other places where inaccuracies are introduced.
-
If they’re pedal-based power meters, you should also verify that you’re compensating for the crank length on your bike. Power meters transmit a torque value that’s read by the head unit / pedal manufacturer’s mobile app. The head unit / mobile app should have a way to input your crankarm length, which then does the conversion to power. Please check the manufacturer sites for both your pedals and your head unit.
-
While you’re looking at the pedal manufacturer’s site - please read their installation instructions carefully. Not to pick on Garmin, but their early generation Vector-series pedals were very sensitive to how tight the pedal axles were installed into the cranks, and specified a torque that you needed a 15 mm crow’s foot socket installed on your torque wrench to measure with precision.
Other brands of pedal-based power meter may also have specific installation instructions. Crank-based power meters should be factory-adjusted for the crank arm length, but worth verifying with the manufacturer.