如何更改select2 onload选项的值？

<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
<link href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.1.0/css/select2.min.css" rel="stylesheet" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/select2/4.1.0/js/select2.min.js"></script>

<select id="mySelect"></select>

$(document).ready(function() {
  $('#mySelect').select2({
    // 设置选项
  });
});

// 获取select2的实例
var select2Instance = $('#mySelect').data('select2');

// 清空当前选项
select2Instance.val(null).trigger('change');

// 添加新的选项
var newOption = new Option('新选项', 'value');
select2Instance.append(newOption);

// 设置默认选中的值
select2Instance.val('value').trigger('change');