Replace example.com with the domain that you want to find real IP address of a website that using Cloudflare. Note that if they configure ftp, mail, subdomain on Cloudflare DNS then these commands will not work, you need to use other ways to find.
Just cuious, why you want to find real IP of a website behind CloudFlare?
The best you can do is hope that something like mail is on the same IP as the site like was described above. Kind of the point behind CloudFlare is that you can't see the true IP and bypass CloudFlare to directly attack it. You could also try dnshistory.org and see if maybe their IP before switching to CF is listed and hope it's the same as it was.