This is confusing to me, and I'm not a novice to WireGuard.

WireGuard is a layer-3 protocol. Given that WireGuard does not natively support DHCP or dynamic internal IP allocation within its encrypted tunnels, and it instead relies on static tunnel IP configurations (Address and AllowedIPs for each pre-registered client), how would a new unregistered client be assigned an IP address within the encrypted subnet?