Seem like 3D Touch feature is a craze these days. Yes, some Android users of Instagram actually found that the app has a 3D feature added to it momentarily there, which the update was removed on the Google Play Store.
Unlike the long press on the pressure-sensitive screen for iPhone, here it works with no special screen required, you just need to long press on the picture thumbnails, and it will pop-up a zoomed-in window which will enable you to, like, comment and share the particular thumbnail on the Instagram user’s profile.
I have tested it personally, just toying, and there was not many functionality to it as for now. Obviously, it seems like a sneak preview and something we expect to see in the future updates.
For those Instagram freaks out there, the new feature is currently available in the Instagram 7.13.0 Apk (HERE) update, since Instagram has reportedly removed it from the Google Play Store.