JSFiddle - React, Tailwind, and code Playground

HTML

<div>
</div>

CSS

div {
    width: 100px;
    height: 100px;
    background: red;
    opacity: 0;
    
    animation: fadeIn 3s;
    animation-delay: 5s;
    animation-fill-mode: forwards;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}