It’s just not true that users don’t like making things opt-out. HN Users tend not to like it but I think a lot of users dislike the alternatives: either because they’re undiscoverable (toggle in settings or a menu) or intrusive (various sorts of what’s new overlays). Imo, the question of when to make things opt-in vs. opt-out is fairly subtle and largely depends on the feature and pre-existing trust.

There are infinite ways on how to inform users of a new feature and ask to activate it.