const test = (strs: string[]) =>
  Object.values(
    strs.reduce((acc, el) => {
      const key = el.split("").sort().join("");
      acc[key] = [...(acc[key] || []), el].sort();
      return acc;
    }, {} as Record<string, string[]>)
  ).sort((a, b) => a.length - b.length);

// ========================

console.log(test(["eat", "tea", "tan", "ate", "nat", "bat"]));
console.log(test([""]));
console.log(test(["a"]));