Is the Host HTTP header only required in version 1.1?

Question

HTTP headers

I'm learning theory for social security, now HTTP. I would like to clarify.
The Mozilla documentation says that headers are optional in the request, but Hostrequired for protocol version 1.1.
I understand correctly that Host is optional in other versions of HTTP: before 1.1, 2.0 and 3?
Overview of HTTP
Header Host

Answer 1

http2 uses the :authority pseudo-header for this .