JSFiddle - React, Tailwind, and code Playground

HTML

<select name="formulario" id="formulario">
    <option value="">--</option>
    <option value="empresa">Empresa</option>
    <option value="cantidato">Cantidato</option>
</select>

<div id="campos">
    <input type="text" value="" placeholder="CNPJ" id="empresa">
    <input type="text" value="" placeholder="CPF" id="cantidato">
</div>

JavaScript

$(document).ready(function() {
    $('#formulario').on('change', function() {
        var tipo = this.value;
        $('#empresa, #cantidato').each(function() {
            var usar = this.id == tipo;
            this.required = usar;
            this.style.display = usar ? 'block' : 'none';
        });
    });
});