A square works when your subject has enough space on both sides to survive the crop. A plate photographed from above, a small product, or a face with a plain background can all make a clear square composition. A group spread across a wide frame is a different problem: forcing it into a square may remove people you meant to include.
Before processing, identify the detail that must remain visible. For a portrait, that might be the top of the hair and both shoulders. For packaging, it might include the cap, the bottom label, and the shadow beneath the object. Move the crop in the preview and check all four edges, rather than judging only the centre.
Our square preset exports 1080×1080 pixels. These are this tool's export settings, not a promise that every Instagram surface displays a square without cropping. Feed, profile, and sharing previews can frame the same post differently. Keep crucial detail comfortably inside the edges, and inspect the preview inside Instagram before publishing.