Do I need any sensors for my bike for the 920XT to receive and/or calculate ride data?
Only if you want cadence, power or heart rate. It’ll use GPS (outdoor riding only) for speed and distance with no additional sensors required.
The watch without anything else will give you… Speed, distance. Speed is not that accurate since it is via GPS, so it’s a bit delayed and can vary a bit.
A good investment is the Garmin Speed/Cadence sensor. This will give you accurate speed and also give you cadence.
Power meter is a while different discussion.