JSFiddle - React, Tailwind, and code Playground

HTML

<div class="one">
</div>
<div class="two">
</div>

CSS

.one {
    background: slategray;
    height: 25px;
    width: 25px;
}

.two {
    background: azure;
    height: 50px;
    width: 50px;
}

.one:hover + .two {
    background: olive;
    width: 50px;
    height: 50px;
}