Trying to get value from settings page field

Hi

I'm trying to use a php function to echo the value of a field on a settings page.

The settings page ID is 'site-details'
the field group id is 'contact-details'
the field id is 'bookings' and it's a URL type field.

the function I used is...

function booking_link() {
    
$value = rwmb_meta( 'bookings', ['object_type' => 'setting'], 'site-details' );
echo $value;

}

Ive obviously got something wrong so any help would be great.