JSFiddle - React, Tailwind, and code Playground

HTML

<select id="dropdwon1">
 <option value="1">Item1</option>
 <option value="2">Item2</option>
 <option value="3">Item3</option>
</select>

<select id="dropdwon2">
 <option value="1">Item1</option>
 <option value="2">Item2</option>
 <option value="3">Item3</option>
</select>

JavaScript

$("#dropdwon1").change(function(){
    $("#dropdwon2").val($(this).val());
});