My dog dont want to eat his food wat can i mix in there to trick him?

Make him some gravy or try soft food

Gravy, ground beef, shredded chicken, wet food, or broth.

A raw egg . Sometimes mixing it up in their food makes them want to eat it when they don't want to. But only do it once.

I'd check the ingredients against the need of his breed and make sure he's getting the right food.

Coconut oil helps too.