What makes an Instagram comment get a reply
Creators read comments in the hour after they post and answer the ones that are easy to answer. A question about something visible in the photo or Reel, a "this worked for me because" story, or a respectful counterpoint all give the creator a reason to type back.
Comments that only praise ("love this", "so good 🔥") are fine for friends, but they look the same as bot comments and get skimmed. The drafts here always point at something in the post.
On Instagram the creator can pin comments to the top of the post, so a comment that adds to the post is the kind that gets pinned and read by everyone who opens it.
Using comments to grow an Instagram account the honest way
Pick a short list of accounts in your niche whose audience you would like to reach. Read their new posts and leave one comment that shows you read it. Do this consistently and the people who reply to your comments start to recognise your name and visit your profile.
Make sure your profile is ready when they arrive: a clear bio within Instagram's 150 characters and a pinned post that explains what you do.
Never paste the same comment on several posts. Instagram treats repeated identical comments as spam, and the accounts you comment on can see it too.