Can we use iPhone as external camera with QT and MBP

Unable to connect iPhone 8 Plus to 2016 MBP via Thunderbolt/USB (dongle) and use the iPhone as an external camera?

Have tried to do this using QuickTime Player.

• We open QTP, chose File>New Screen Recording
• Screen Recording controller appears.
• We click the down arrow… but the iPhone does not appear.

Are we doing something incorrectly? Or, are we doing something that cannot be done?

(Have gone to System Preferences to allow QTP use of Mic and Cam.)

Thanks!