JSFiddle - React, Tailwind, and code Playground

HTML

<select class="select_menu">
                                                            <option value="1" selected> ferfer </option>
    <option value="2">frefr</option>
    <option value="3">frefre</option>
    <option value="4">fcderfre</option>
    <option value="5">fwefre</option>
    <option value="6">frefre</option>
    <option value="7">frefe</option>
    <option value="8">rgrtg</option>
    <option value="9">gtrhyt</option>
    <option value="10">grtg</option>
    <option value="11">grthyt</option>
    <option value="12">ythyt</option>
    <option value="13">yt4rtg4r43</option>
    <option value="14">423423</option>
    <option value="15">546</option>
    <option value="16">6554645</option>
    <option value="17">54645</option>
    <option value="17">hythty</option>
                                                       <option value="18">Другое</option>
                                                        </select>
<input type="text" class="form_input hidden ">

SCSS

.form_input {
    &.hidden {
        display:none;    
        &.active {
            display: block;   
        }
    }
}

JavaScript

$(function() {   
    $(".select_menu").change(function() {
        if ($(this).val() == "2"){
            $('.form_input.hidden').addClass('active');
        }
    })
});