Twitch - Big emotes.js

// ==UserScript==
// @name     Twitch - Big emotes
// @version  1
// @grant    none
// @match		 https://www.twitch.tv/*
// @run-at   document-start
// ==/UserScript==

// 

(() => {
  const callback = (mutationsList, observer) => {
    mutationsList.forEach((mut) => {
        if(mut.addedNodes.length === 0) return;
        mut.target.querySelectorAll('.chat-line__message--emote[srcset*="1.0"]').forEach((el) => {
            el.srcset = el.srcset.replace(/1.0/g, '2.0');
            el.src = el.src.replace(/1.0/g, '2.0');
        });
    });
  };
  
  const observer = new MutationObserver(callback);
  observer.observe(document.body, { childList: true, subtree: true });
  
  if(window.observer) window.observer.disconnect();
  window.observer = observer;
})();