I carry a 15.6" laptop and use the Luggageworks Stealth Premier Multi-Purpose Cube. It works well. While it has a large built-in cooler, I typically don't use it as a cooler, just as more storage.

https://luggageworks.com/collections...i-purpose-cube

The actual dimensions of my laptop are 14" x 10.5" and it fits perfectly. I googled the 16" macbook pro dimensions it shows 14.01" x 9.77", so if that's what you have, it'll fit.