How do I lock stolen AirPods?

On your Apple Device Go into the Find My app and press devices at the bottom press on your AirPods and scroll down to Lost AirPods and press on it then follow the on screen instructions you can also buy replacement AirPods from Apple.com or the Apple Support App

What you can do depends somewhat on the particular model of AirPods …

But follow this guide:

Find your lost AirPods with Find My - Apple Support

And this presents essentially the same info in a different format (page navigation arrows at bottom)

Locate AirPods in Find My - Apple Support