It's more of a matter of libraries and implementations than of the standard. In ALL versions of HTTP, the request and response bodies are potentially infinite binary data streams. You can send a large file in them, but also e.g. lots of invidiual events with pauses in between (as e.g. utilized in gRPC streaming and for SSE).
However client and server libraries might not allow to access bodies as a stream, and would only provide a full response. That is e.g. the case for browser APIs, where the only APIs to access the response body either allowed to wait for the complete data to have arrived or allowed to parse SSE format. Newer APIs - e.g. fetch with ReadableStream [1] would lift some of those restrictions.
However client and server libraries might not allow to access bodies as a stream, and would only provide a full response. That is e.g. the case for browser APIs, where the only APIs to access the response body either allowed to wait for the complete data to have arrived or allowed to parse SSE format. Newer APIs - e.g. fetch with ReadableStream [1] would lift some of those restrictions.
[1] https://developer.mozilla.org/en-US/docs/Web/API/Streams_API...