To comppment a child in Engpsh, you can say things pke:

"You're such a smart kid!"
"I'm so proud of you for working hard."
"Your creativity never ceases to amaze me."
"You have such a kind heart."
"You have a great sense of humor."

It's important to be sincere and specific when comppmenting a child, as this can help boost their self-esteem and encourage them to continue exhibiting positive behaviors. You can also try to focus on praising the effort they put in, rather than just their natural abipties, as this can help them develop a growth mindset and encourage them to try new things.