You'll likely be getting lots of input on this but from my own experience and what I've read outdoor FTP is typically higher than indoor. I'm about 8% higher outside. I've heard of many reason for this; cooling, momentum outdoors, motivation etc. Training Peaks has an interesting article on the subject.
https://www.trainingpeaks.com/blog/adjusting-your-functional-threshold-power-for-indoor-riding/
Outdoors your power will jump all over the place and depends on what your averaging is set to. I have a 3 second power on my Garmin 510 and it jumps a lot, especially when it's windy or on bad roads. I also have a field for Lap NP and set my autolap to 1 mile, that seems to help me smooth out the entire ride a bit.
https://www.trainingpeaks.com/blog/adjusting-your-functional-threshold-power-for-indoor-riding/
Outdoors your power will jump all over the place and depends on what your averaging is set to. I have a 3 second power on my Garmin 510 and it jumps a lot, especially when it's windy or on bad roads. I also have a field for Lap NP and set my autolap to 1 mile, that seems to help me smooth out the entire ride a bit.