How to test on pre-production environment not impacting the production?

Usually we will have a pre-production environment for verification before prod.

And many articles suggest that the pre-production's DB, environment settings are all same with prod.

So here is my question, when we do testing on pre-production, we are operating the prod data, and we may have automation jobs running on this pre-production, once deployed, it will probably send emails/SMS to the real customer, or even make payments. But if we disable these features, we can't verify the end-to-end process.

How can we make sure we verify the code without impacting the business? Is there any kind of isolation needed, and how?