Works shockingly well — but prepare to wait as it works, as Instagram rate limitations means any action takes ~15 seconds, or Instagram will temporarily freeze your account. So be patient, as the speed has nothing to do with PostsCleaner .
Yes, a (very reasonably priced) paid subscription is required for use, but it’s worth it.
My use case: Mass archiving 2,000 Instagram posts. It’s taking 10+ hours (I am halfway done as I write this), and you need to leave PostsCleaner open for it to work (not in the background, but open on the screen), but it does indeed do as described. Fortunately PostsCleaner automatically prevents your iPhone from sleeping, so you could let it run overnight.
Great filtering features (e.g. date, keywords, number of likes or comments) to take action only on the posts you want to.