One fast, free way to grow your Instagram is to consistently post short-form videos (Reels) using trending audio and niche hashtags.
Focus on Reels because the Instagram algorithm tends to push them to non-followers, giving you reach without spending money. Pick one clear niche (fitness, food, study tips, etc.), and post regularly so the system can “learn” who to show your content to.
If you want faster results, always hook viewers in the first 2–3 seconds and keep videos under ~15–30 seconds so they’re more likely to be watched to the end.