You do if you want to use UDP multicast or want to enumerate MDNS services. That's what this article is about. If I understand correctly, they apparently don't even let you use multicast on your own phone for testing without requesting permission.
However, I was partially wrong (it's been some time since I needed this), you can actually use them in the simulator without an approval.
List of special entitlements needing an approval: https://stackoverflow.com/a/65330176
Additionally, I know that CarPlay entitlements need an approval: https://developer.apple.com/documentation/carplay/requesting...
Only if you want to create a wildcard listener. If you know the exact name of the service you want to listen out for, you do not need the entitlement.