Basically right now when users add hashtags, they will have to type it in manually. However according to her findings, it seems that Instagram is testing allowing users to select hashtags from a list which at the same time also seems to hide them and prevent them from showing up in captions in your posts.
Instagram is testing the ability to add hashtags to posts without including it in the post caption pic.twitter.com/OhQn0xcCuw
— Jane Manchun Wong (@wongmjane) September 20, 2018
Presumably these hidden hashtags will continue to function as per usual to help users discover posts, but also help to clean up captions by not having them filled with hashtags. Speaking of reach, Instagram is also testing out something that could limit the reach of posts. Wong also discovered that Instagram is testing geofencing for posts and stories.
https://twitter.com/wongmjane/status/1042639805677330433
Similar to how Facebook posts can be targeted by language or region, this is a feature that Instagram appears to be testing as well, where it will limit posts to certain regions which could be useful for brands who might want to launch marketing campaigns for different countries but not have them flood the feed of their followers. These are currently in testing and there’s no word on when they might be made available, if at all.