From Bookbub.com:
If you do think it’s worth testing the platform[Instagram] out, here are some great examples of authors who’ve been able to successfully build an audience and publish content that connects with their readers. We’ve included a variety of authors, both traditionally and independently published, who write in different genres, and encourage you to scroll through their feeds to see the full breadth of content they post. We hope this will help give you inspiration for what to publish on your own Instagram.