Can you find a lost AirPods Pro case if you have both AirPods with you?

No, unfortunately not. But you can try to locate them like this:

1. Open the Find my app on your iPhone
2. Check the list of devices you’ve paired with your iPhone and tap the option showing AirPods
3. Check if your AirPods have a green light next to their name 
4. If there’s a green dot, then that means that the case is nearby
5. If you see a grey dot instead, then that means that your AirPods case is not around. Grey light suggests that it is out of range
6. For green dot, tap the play sound option to play loud music on your AirPods and track them by following the music
7. If offline, tap the Car icon to see the last location of your AirPods