How do you say he is called declan in French?

There are a few ways to say "He is called Declan" in French, depending on the context and formality:

Formal:

* Il s'appelle Declan. (This is the most common and neutral way to say it.)

* On l'appelle Declan. (This literally translates to "He is called Declan" but is less common.)

Informal:

* Il s'appelle Déclan. (This is the same as the formal version but uses the French spelling of the name.)

* C'est Déclan. (This translates to "It's Declan" and is more casual.)

For emphasis:

* Son prénom est Declan. (This means "His first name is Declan.")

The best option depends on the context and your relationship with the listener.