I checked this answer but to achieve the same result, that is to get case-insensitive sorting, I need to use orderBy instead of sortBy since
The documentation specifies that you can pass a function as "iteratee":
[iteratees=[_.identity]] (Array[]|Function[]|Object[]|string[]): The iteratees to sort by.
So you can do
const users = [
{ name: 'A', age: 48 },
{ name: 'B', age: 34 },
{ name: 'b', age: 40 },
{ name: 'a', age: 36 }
];
const sortedUsers = _.orderBy(users, [user => user.name.toLowerCase()], ['desc']);
console.log(sortedUsers);