How to add a code on header for homepage only?

It would look something like this:

add_action( 'wp_head', function() {
	if ( is_front_page() )
		echo '<meta />';
} );

You forget to mention the file I have to insert it. Where to add this code? I guess theme’s header.php. is it?

I would put it in a child theme’s functions.php

Thanks