JSFiddle - React, Tailwind, and code Playground

HTML

<select name="listku" >
    <option value="1">1</option>
    <option value="2">2</option>
    <option value="3">3</option>
    <option value="4">4</option>
    <option value="5">5</option>
    <option value="6">6</option>
    <option value="7">7</option>
</select>

<div id="jmena">

</div>

JavaScript

$("select[name=listku]").change(function() {

   var pocetInputu = $("#jmena input").length;
   var pozadovanyPocet = $(this).val();
   rozdil = pozadovanyPocet - pocetInputu;
   
   if(rozdil > 0)
   {
      for (var i = 0; i < rozdil; i++) {
          $("#jmena").append('<input type="text" name="jmeno[]" value="" />');
      }
    }
})