I don’t know why I can’t use the function of screen mirroring after updating to iOS 16.3!

AirPlay 2–compatible TVs and other Products --> See all AirPlay 2–enabled smart TVs

If you find your device in the link provided above then --> Use AirPlay to stream video or mirror the screen of your ...

Else Plug a Lightning Digital AV Adapter or Lightning to VGA Adapter into the charging port on the bottom of iPhone. Connect an HDMI or VGA cable to the adapter. Connect the other end of the HDMI or VGA cable to the monitor, TV, or projector. If necessary, switch to the correct video source on the monitor, TV, or projector.

Connect iPhone to a display with a cable - Apple Support (IN)