How to show seconds in macOS 12.7.6 menu bar clock?

Apple shifted things around a bit in macOS Monterey (12.x), moving the clock settings out of the old Date & Time pane and into the Dock & Menu Bar settings.

Here is exactly where to find it:

1. Open System Preferences (from the Apple menu  or your Dock).
2. In the sidebar on the left, scroll down to the Control Center section and select Clock.
3. Check the box next to Display the time with seconds.

The change should apply instantly, and you'll see the seconds ticking away in your menu bar.

Monterey > System Preferences > Dock & Menu Bar > Clock:

I don't know where things are located in Monterey, but in Sequoia, this control is in System Settings > Control Center > Clock > Clock Options… (Display the time with seconds).