JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="a"></textarea>

JavaScript

var t = document.getElementById("a");
t.style.height = "80px";
t.onkeyup = function(e){
    if(e.keyCode == 13){
        t.style.height = parseInt(t.style.height) + 30 + "px";
    }
}