To create custom Unsubscribe Links in the HighLevel email builder:

1. Create a landing page with messaging you want people to see when they unsubscribe

2. Use the url to the landing page from Step 1 to make a Trigger Link

3. Replace the default unsubscribe link url with the Trigger Link

4. Create a Trigger that uses "Trigger Link Clicked" as the condition and "Set Contact DND" as the action