6 WhatsApp messages to congratulate someone:

1. Felicitations: It means good wishes
For example: I extend the felicitations of my family to you. You have achieved a great milestone in your career. 

2. Hip Hip Hooray: This is cheered 3 times in a row 
For example: Our team won the deal! Three cheers for our team! Hip Hip Hooray! Hip Hip Hooray! Hip Hip Hooray!

3. 3 cheers for: Here, '3 cheers' is usually followed by a name or something that you are cheering for. 
For example: 3 cheers for the newlyweds!

4. Kudos is used for expressing praise.
For example: Kudos to you for doing such a fantastic job. 

5. Hats off to you: This is used for showing respect
For example: Hats off to you for winning such a tough competition. 

6. Mazel tov: a Jewish phrase expressing congratulations or wishing someone good luck.
For example: A chorus of mazel tovs greeted the newlyweds.