>>15683694
Yes and no.
You can grind through most of the earlier levels on auto if you have the appropriate levels and gear, you don't even need particular strong units.
On later levels this becomes less doable but you can still auto if you use top tier units and loadouts and fill out your fleet at the cost of resource efficiency.
On the latest levels this is impossible even with top tier everything until you complete the level enough times to get the danger level of it down to get a -50% damage taken advantage.
So yes you can eventually auto everything but you'll need to progress enough to make it possible.
Once you hit that pinnacle the game stops being challenging unless you're trying to maximize resource efficiency.
This is inline with what the devs intend though - you can tell they really want their game to be as comfy and casual as possible while still remaining a game.
Oh and there's also EX mode during events that is impossible to auto, but those are just touhou lite challenges and don't actually give you any rewards outside of fun.