Instagram has just announced that as of today you can zoom in on photos and videos in feed, on profiles and on Explore.
All you have to do is pinch the photo/video to expand and/or retract.
Per their IG post, the ZOOM update is coming to iOS today. Android users, sorry, but it looks like you'll have to wait.
The move comes after the social media platform just recently introduced its Instagram Stories feature that is eerily similar to Snapchat.