I believe that the main trigger for autophagy is AMPK and the main thing that halts/prevents it is mTOR (more systemic mTOR, not muscle mTOR).
When you are fasting for a significant period you will trigger AMPK (which is activated when you need to mobilize stored energy). If you fast for 16 hours and then eat above maintenance you will have an AMPK release during the fast and then you will have a large mTOR activation during the eating period.
Thus you can stimulate autophagy during the fasted period but it will be halted during the eating period. Even if you are to consume a supra-maintenance level of calories after your fast, it has no impact on that is happening during the fast. While you can have a surplus over the course of the 24h period, you are in a deficit during the fasting period and you need to mobilize stored energy which means that you will release AMPK and start autophagy.
Of course, the longer the fast, the more autophagy you will get.
As far as dry vs. hydrous fasting, I couldn’t say. I know that Jocke swears by dry fasting. But I’m not sure if you can actually measure the difference in autophagy between both, if any.