Trying it just now on konsole, it does not. Whether that's because your terminal is following standards or because your terminal is interpreting a terminal command that doesn't actually say anything about scrollback to also clear scrollback, I don't know, and await anyone who does to answer that question.
My gut is that the terminal protocol would know nothing about scrollback and thus not have a "clear scrollback" command in it directly. There are plenty of other indications that scrollback is basically a hack.
[Konsole] Settings -> Configure Keyboard Shortcuts ... "Clear Scrollback and Reset". On my Arch boxes it is mapped to Ctrl + Shift + k. That's probably a default from upstream.
It's a common feature, but not formally standardized.
ED 3 isn't actually in the [ECMA-048] spec.
It was an xterm feature introduced in June 1999. Several terminal developers later adopted the feature. In April 2011, a Red Hat developer submitted a patch to the Linux kernel, modifying its console driver to do the same thing.
So it's not a formal standard, but it's universal on Linux since 3.0 and many terminal emulators have adopted it.
This history is covered in [clear(1)] from the ncurses project.
... none of which contradicts the point that the protocol does know about scrollback. The aforementioned developer, Petr Písař, got the implementation wrong, note.
My gut is that the terminal protocol would know nothing about scrollback and thus not have a "clear scrollback" command in it directly. There are plenty of other indications that scrollback is basically a hack.