.accordion-item:target .answer {
max-height: 20rem;
}
<div class="accordion-item" id="question1">
<a class="accordion-link" href="#question1">What is COVID-19?
<ion-icon class="ion" name="add-outline"></ion-icon>
<ion-icon class="ion" name="remove-outline"></ion-icon>
</a>
<div class="answer">
<p>
COVID-19 is the infectious disease caused by the most recently discovered coronavirus. This new virus and disease were unknown before the outbreak began in Wuhan, China, in December 2019.
</p>
</div>
</div>
The height of the answer class isn't getting maximised to 20rem after I click on that class (accordion-item).