JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://select2.github.io/dist/js/select2.full.js"></script>
<link rel="stylesheet" href="https://select2.github.io/dist/css/select2.min.css">
<select class="js-example-basic-multiple" multiple="multiple"  style="width:100%">
    <option value="月曜日">月曜日</option>
    <option value="火曜日">火曜日</option>
</select>
<br /><br /><br /><br /><br />
<div id="some_wrapper">
    
</div>
<button type="button" name="imgSU" class="btn btn-warning btn-md margintop15" id="add-new">+</button>

JavaScript

$('.js-example-basic-multiple').select2();

$("#add-new").on("click", function() {
var clone_temp = $(".js-example-basic-multiple").clone();
$("#some_wrapper").html(clone_temp);
clone_temp.select2()
 });