JSFiddle - React, Tailwind, and code Playground

HTML

<div>
        <img src="http://lorempixel.com/50/50" />
        <img src="http://lorempixel.com/50/50" />
        <img src="http://lorempixel.com/50/50" />
    </div>

CSS

div img:nth-child(1):nth-last-child(3),
div img:nth-child(1):nth-last-child(3) ~ img {
    border-radius: 50%;
}