JSFiddle - React, Tailwind, and code Playground

HTML

<div class="comment" contenteditable>hello world<br>foo bar</div>

<div class="comment" contenteditable>Hakuna Matata!</div>

CSS

.comment {
  border: dashed 3px gray;
  margin: 1em;
  padding: 0.5em;
}

JavaScript

document.querySelectorAll('.comment').forEach(comment => {
  comment.addEventListener('keydown', myBrHandler)
})

function myBrHandler(e) {
  if(e.ctrlKey && e.keyCode == 13){
    let brNode = document.createElement('br'),
    last = false;
    
    let range = window.getSelection().getRangeAt(0);
    if (!range.endContainer.nextElementSibling) {
    		last = true;
    }
    range.deleteContents();
    range.insertNode(brNode);
    if (last) {
    		let brNode = document.createElement('br')
    		range.insertNode(brNode);
    }
    range.collapse();
  }
}