How to map such a grid?

Question

React

Answer 1

Just like a regular list: Set the increased width via css:
{items.map(n => <div className="item">...</div>)}

.item:nth-child(6n + 3),
.item:nth-child(6n + 4) {
  ...
}

https://jsfiddle.net/exfk10Ls/1/