DiskMaker X is my go-to app for creating bootable version of macOS updates on a USB drive. It’s free, it’s easy, and it’s near perfect. While macOS has a built in recovery disk, a bootable USB drive is great for when the drive is malfunctioning or for quick OS updates (without having to download a 5GB file). Download it, install it on a USB drive, and you are good to go.
DiskMaker X is a free download, and donations are accepted.