Meta’s pixel has a built-in consent mechanism. You load the pixel code but tell it to hold back until you grant permission. This is cleaner than not loading the script at all, because once consent arrives you don’t need to re-initialise anything.

<script>
  !function(f,b,e,v,n,t,s){/* standard Meta Pixel base code */}
  (window, document,'script','https://connect.facebook.net/en_US/fbevents.js');

  // Hold all tracking until the visitor decides
  fbq('consent', 'revoke');
  fbq('init', 'YOUR_PIXEL_ID');
  fbq('track', 'PageView');
</script>

With consent set to revoke, events are queued rather than sent. When the visitor accepts marketing cookies, your CMP calls:

fbq('consent', 'grant');

The queued PageView is then sent, and tracking carries on normally. If the visitor later withdraws consent, call fbq('consent', 'revoke') again and clear the _fbp cookie.

Most CMPs fire a JavaScript event or callback when consent changes. Here’s the pattern, using a generic event name; check your CMP’s documentation for the exact one:

window.addEventListener('consentChanged', function (e) {
  if (e.detail.marketing === true) {
    fbq('consent', 'grant');
  } else {
    fbq('consent', 'revoke');
  }
});