JSFiddle - React, Tailwind, and code Playground

HTML

<div class="box">
    <button id="expander">click to expand</button>
    <p>there is many content with unknown height...</p>
    <p>second paragraph</p>
    <p>third paragraph</p>
    <p>fourth paragraph</p>
</div>

CSS

.box {
    width: 300px;
    max-height: 30px;
    overflow: hidden;
    background: #aaa;
    -webkit-transition: max-height 400ms ease-in-out;
    -moz-transition: max-height 400ms ease-in-out;
    -ms-transition: max-height 400ms ease-in-out;
    -o-transition: max-height 400ms ease-in-out;
    transition: max-height 400ms ease-in-out;
}
.box.open {
    max-height: 999px;
}

JavaScript

$('#expander').on('click', function () {
    $('.box').toggleClass('open')
});