This is largely based on how you interact with those accounts, so if there is an account you like or comment more on, then those posts will be at the top, and so on. However, if you miss the good old chronological feed, Instagram has announced that it will be returning in the form of “Favorites”.
https://twitter.com/instagram/status/1506722074810720257
Basically this list of “Favorites” is a curated list where you can add accounts you are more interested in to the list. According to Instagram, posts in your Favorites feed will be chronological, meaning you see accounts that you might be more interested in, like maybe friends or family.
If you want to go back to your regular feed, you can select the “Following” section which will take you back to the original feed based on Instagram’s algorithm. The update should already be rolling out to Instagram users, so check it out if this is something you’ve been waiting for.