Here’s what Lockdown Mode on your iPhone does:
Message Attachments are blocked, except for images.
If a website has a complex tech, like just-in-time (JIT) Javascript compilation, it will be disabled.
FaceTime calls, and other incoming invitations and service requests, from unknown callers are blocked.
Shared albums will be removed from the Photos app, and new invites will be blocked.
You cannot connect to a computer through a wired connection.
If a corporate or school network sends you a configuration profile to define settings, this will be blocked when the iPhone is locked.
Do you have questions about Lockdown Mode? Let us know.
Sources: 9to5 Mac; Music by BenSound