I think it's because Instagram wants to provide a more immersive experience. The larger size allows for more details and better display of photos and videos.
Instagram stories are big because they're visually engaging and allow for a lot of creativity. Also, they disappear after 24 hours, adding an element of exclusivity and urgency.
Instagram stories can vary in size. Generally, they are displayed in full-screen mode on your phone, so they take up a significant portion of the screen.
They're big because they allow for creativity and personal expression. Users can add filters, stickers, and text to make their stories stand out. Plus, it's a great way for businesses and influencers to engage with their audience.
Maybe it's to make the content more visible and engaging. Bigger stories could catch your attention more easily.
It could be that the format or aspect ratio of the content you're uploading doesn't match the standard Instagram requirements, causing it to appear big. Also, if you're using third-party apps for editing before posting, they might be altering the size. Have a look at these aspects to solve the issue.
There could be a few reasons. One possibility is that you're using a camera app with high-quality settings. Another is that the app itself might have some default settings that are causing the stories to be large. You could check both your device and the Instagram app settings to see if there's anything you can adjust.