JSFiddle - React, Tailwind, and code Playground

JavaScript

var arr = [
    ['firstname1', 'lasname1', '26'],
    ['firstname2', 'lastname2', '14'],
    ['firstname3', 'lasme3', '22'],
    ['firstname3', 'laname3', '22'],
    ['firstname4', 'lasame4', '23'],
    ['firstname2', 'lastname2', '14'],
    ['firstname5', 'lastnme5', '20']
];

console.log(arr.sort((a, b) => b[0] < a[0]))