github bitcoin/doc/tor.md – Automatically versus Manually creating a Bitcoin Core tor onion service

The doc I’m asking about: TOR SUPPORT IN BITCOIN. Section 1 describes how to “Run Bitcoin Core behind a Tor proxy.” Then…

  1. Automatically create a Bitcoin Core onion service

(I)f Tor is running and proper authentication has been configured,
Bitcoin Core automatically creates an onion service to listen on.

This section describes how to establish proper authentication.

  1. Manually create a Bitcoin Core onion service

You can also manually configure your node to be reachable from the Tor
network. Add these lines to your /etc/tor/torrc (or equivalent config
file):
HiddenServiceDir /var/lib/tor/bitcoin-service
HiddenServicePort 8333 127.0.0.1:8334

This section then describes the externalip, listen, and discover command line or bitcoin.conf options.

I am confused about the relation of sections 2 and 3. Are they alternatives or is 3 additive to 2? If the user, per section 3, adds the HiddenService… lines to torrc, and includes externalip=(user's public 64-char code).onion and listen=1 in bitcoin.conf, can the authentication steps of section 2 be omitted? The externalip with the user’s onion address of section 3 seems to provide advertising of the node’s reachable tor address. But if it’s omitted, how do inbound peers contact the onion service that, per section 2, is being “listen(ed) on”?