it's c-x followed by c-e although no need to release the control key that I'm aware of. The c-x is in the same family as alt-x (sometimes called "meta-x") which is a similar Emacs "mode switching" leader keystroke

You can read about the gory details in "man 3 readline": https://manpages.ubuntu.com/manpages/jammy/en/man3/readline....