Where to place a filter hook

I'am using Contact Form 7 with Google recaptcha integration. I consider to change the recaptcha threshold: FAQ Contact Form 7 recaptcha

This is the code:

add_filter( 'wpcf7_recaptcha_threshold',
 
  function( $threshold ) {
    $threshold = 0.3; // decrease threshold to 0.3
 
    return $threshold;
  },
 
  10, 1
);

Where can I put this code ? Appearance>Elements>Hook: what location ?
Or should I use put this code in the Code Snippets Plugin?

Thanks !

Frans