Answering my own question for those searching.
Yes, make-ssl-connect@ tracks protocol recommendations. [1] shows that make-ssl-connect@ uses `ssl-make-server-context' with default arguments, meaning an `auto' protocol. The server context docs point to client context docs for the meaning of `'auto'. Quote: "Automatically negotiates the protocol version
from those that this library considers sufficiently secure—currently
TLS versions 1.0 and higher, but subject to change."
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐