Caixa sem restrições Flutter

// this box can give whatever size you want despite the size of the screen or
// it's parent's size.... but will give you overflow error if any...

UnconstrainedBox(
      child: Container(color: red, width: 40, height: 50),
    )
  
// if you don't want any overflow error then prefer using 'overflowbox' instead.
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