se 2020 continuity camera... how?

Note that the Apple Support article

Use your iPhone as a webcam on your Mac - Apple Support

... has a list of what to check if you don’t see your iPhone as a camera or microphone option in an app such as FaceTime or Photo Booth. At the risk of being redundant, here is that list:

1. Connect it to your Mac with a USB cable and check again. (If it’s already connected with a cable, disconnect it and reconnect it.)
2. Check the following:

• • Your iPhone is an iPhone XR or later.
  • Your iPhone has the latest version of iOS 16.
  • Your Mac has the latest version of macOS Ventura.
  • Your iPhone has Continuity Camera Webcam turned on in Settings > General > AirPlay & Handoff.
  • Your iPhone recognizes the Mac as a trusted computer. See the Apple Support article About the ‘Trust This Computer’ alert on your iPhone or iPad.
  • Your iPhone and Mac have Wi-Fi, Bluetooth, and two-factor authentication turned on.
  • Your iPhone and Mac are signed in with the same Apple ID. (This feature doesn’t work with Managed Apple IDs.)
  • Your iPhone and Mac are within 30 feet of each other.
  • Your iPhone isn’t sharing its cellular connection, and your Mac isn’t sharing its internet connection.