C26 Coach Robbie talks about FTP and the differences between riding inside on the trainer and going outside.
You don’t change your power based on terrain, you change your cadence based on the power you’re supposed to maintain.
If you can get outside consistently with a power meter, it’s a good time to get out and readjust. Power outside, for many is significantly higher. The watts or zones of the effort level is much different.
It’s physically and emotionally harder to produce power inside.