Get chid element
HTML
<div id="root"></div>
JavaScript
const wrapper = document.createElement('div');
wrapper.innerHTML = `
<div class="parent">
<div class="child">child</div>
</div>
`;
root.append(wrapper);
const [childElement] = wrapper.getElementsByClassName('child');
childElement.innerHTML = `
<a href="https://google.com">Google</a>
`
console.log('childElement', childElement);