JSFiddle - React, Tailwind, and code Playground

HTML

<a href="#">
    <img src="/favicon.png" classe="SOMENTE AQUI" />
</a>

<a href="#">
    <img src="/favicon.png"/>
</a>

<a href="#">
    <img src="/favicon.png"/>
</a>

CSS

.novaClasse {
    border: red 2px solid;
}

JavaScript

document.querySelector('a img').classList.add('novaClasse');