Is there a way to detect if a user is visiting my website for the first time, and if so, redirect them to a page, for example, index-first-time-visitor.php - and if they are not a first time visitor, it sends them to index.php
If there is a way to do this, please demonstrate how.
Put this at the top of your index.php
The cookie will live for 10 years, after that, a user will be a "new" visitor again.