⤷ Change size of other window

Use FindWindow function to find handle of the foreign window and MoveWindow function to change position and dimensions of this window.

procedure TForm1.Button1Click(Sender: TObject);
var
  MyHandle: THandle;
  WinRect: TRect;
begin
  MyHandle:=FindWindow(nil, 'Delphi Help');
  GetWindowRect(MyHandle, WinRect);
  MoveWindow(MyHandle, WinRect.Left, WinRect.Top, 300, 300, True);
end;
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