How can I tell if I have TCF enabled?

There are subtle differences between a standard banner with and without TCF enabled. The most noticeable would be that the banner that does not have TCF enabled has three tabs: "Consent", "Details", and "About". When TCF is enabled, an additional "Ad Settings" tab is available.
This tab is populated with "Purposes", "Features", and "Partners". This both provides information and allows a user to enable and disable each separately, or enable or disable all of these purposes, features, and partners.

You can tell if TCF is enabled by checking if the __tcfapi stub is available by issuing this command in the developer console in your browser: "__tcfapi" in window

This returns "true" if TCF is enabled. Conversely this returns "false" if TCF is not enabled.