JSFiddle - React, Tailwind, and code Playground

HTML

<span id="toBeAffected"> Ciao </span>

<div class="sibiling">
    <div>
        <input id="trigger" type="checkbox"/>
    </div>
</div>
...

CSS

.sibiling:has(input:checked)  ~  #toBeAffected {
    font-weight: bold;
}