1. Use Trending Songs.
2. Post on Correct Time
3. Create suspense in your video
4. Use viral Hashtag
Come here to know how you will do these point
Having viewers click on the music in your Reels indicates to Instagram that they want to use that music so only use trending songs
See Trending Songs Here
Do hashtags work on reels viral on Instagram?
Yes. You'll want to add hashtags on the caption page of your Instagram reel while creating the post. You can also check Here the correct hashtags for your reels.
Don't expect to post one Reels and reach hundreds of thousands of people. Quite the opposite, the more you post, the higher your reach and engagement grow over time. For starters, you can try posting one Reels daily, come here in detail know.