The total number of your followers is nothing more than a vanity metric. What you really need is a good engagement rate and a follower audit can help you with this.
Engagement rates are calculated as a percentage of your followers who engage with your content through likes, comments and shares etc. So, if you have 100 followers and 50 of them regularly engage, your engagement rate is 10x better than someone who has 1000 followers, if they also have 50 who regularly engage.
We know that the Instagram algorithm favours those with higher engagement rates, so if you think you have lots of followers who don’t regularly engage, it’s time for a follower audit.
Make a note of your current engagement rate and then scroll to the bottom of your follower list to get to your oldest followers. Remove any ghost / span / inactive profiles and remove any that you think are not your target audience anymore. Then calculate your engagement rate again.
Your follower count will have decreased but your engagement rate will have increased.