Easy way to update posts in bulk?

So we’ve introduced some functionality which requires us to update some ~6,000 posts. Enabling the feature is done at a post level and there isn’t any easy or obvious way to do it across the board.

Are there any reputable plugins for bulk-updating posts? I’ve been looking at doing this via phpmyadmin, but part of the process is tied to the post being updated. We check a box which flips a bit in a custom field, and the post update then populates the other necessary fields.

Any ideas?