square-small from coolicons in Line with regular corners. box, rectangle, stop, checkbox, frame, tiny. Other styles and corners: @coolicons/<style>/<radius>/square-small with line, duocolor, duotone, fill or bulk and sharp or round. Leave out regular, like @coolicons/fill/square-small, and use @coolicons/square-small for line with regular corners.
pnpm dlx shadcn@latest add "https://coolicons.cool/r/square-small.json"