Как сравнить подмассивы?

const arr = [ 
  [10, 10, 10, 20, 60], 
  [10, 10, 50, 10, 10], 
  [20, 10, 30, 20, 10] 
]; 
 
const arrLength = arr.length; 
const subArrLength = arr[0].length; 
const flattenArr = [].concat(...arr); 
const result = []; 
 
for (let i = 0; i < subArrLength; i++) { 
  const indexes = []; 
   
  for (let j = 0; j < arrLength; j++) { 
    indexes.push(flattenArr[i + j * subArrLength]); 
  } 
 
  result.push(Math.max(...indexes)); 
} 
 
console.log(result); // [20, 10, 50, 20, 60];

function* nextMax(arr, index) { // получаем массив соответствующий колонке index 
  for (var i = 0; i < arr.length; i++) { 
    yield arr[i][index]; 
  } 
} 
 
var arr = [ 
  [10, 10, 10, 20, 60], 
  [10, 10, 50, 10, 10], 
  [20, 10, 30, 20, 10] 
]; 
 
var dest = arr[0].map((cur, i) => Math.max(...(nextMax(arr, i)))); 
 
console.log(dest);

var arr = [ 
  [10, 10, 10, 20, 60], 
  [10, 10, 50, 10, 10], 
  [20, 10, 30, 20, 10] 
]; 
 
var dest = arr.reduce((acc, cur) => 
  acc.map((el, i) => Math.max(el, cur[i])) 
) 
 
console.log(dest);