It's all about Maximizing the Reach that your post gets, and this depends on content quality, used hashtags, the engagement your post gets in the first hour and the list goes on.... All this determine whether if your post gonna rank on the explore page or not.
One hack i usually use to know which content will rank on the explore page, I just go and like my competitors posts then my explore page changes constantly then i just try to see what does my specific explore page has in common when I find a post that keeps showing I know it works for my competitors just fine then it's gonna work for me.
To sum up it all depends on the consistency and posting hight quality content with strong cpas that encourages users to share, save, comment, like