JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="notesfield" maxlength="40" rows="1" onkeyup="newline()" class="notes">Notes go here.</textarea>

JavaScript

window.newline = function()
{
    x = document.getElementById("notesfield").value.length;
    if (x >= 40)
    {
        document.getElementById("notesfield").rows="2";
        document.getElementById("notesfield").maxlength="80";
    }
}