There are some hashtags that you should follow on Instagram.
Your own branded hashtags: To stay on top of engagement and monitor your reputation. Users may not always tag your business in the same post where they use your hashtag.
Hashtags of your competitors: To keep an eye on them.
Industry hashtags: To stay on top of news and trends in your niche.
To follow a hashtag, simply search for that hashtag and select the "Follow" button in the search results.