JSFiddle - React, Tailwind, and code Playground

HTML

<div>Many</div><div>Lines</div><div>Goes</div><div>Here</div>

JavaScript

function insertAfter(referenceNode, newNode) {
    referenceNode.parentNode.insertBefore(
        newNode,
        referenceNode.nextSibling);
}

var divTags = document.getElementsByTagName('div');

for (var i = 0; i < divTags.length;) {
    var div = divTags[i];
    var text = document.createTextNode('');
    
    text.nodeValue = div.innerHTML;
    div.parentNode.replaceChild(text, div);
    
    insertAfter(text, document.createElement('br'));
}