How to expand aliases inline in zsh?

Just press C-x a, not C-x-a (C-x is a prefix). It will call _expand_alias function to expand the alias.

Moreover, you can add this line to your zshrc then you can expand alias just with TAB:

zstyle ':completion:*' completer _expand_alias _complete _ignored

A full example zshrc:

autoload -Uz compinit; compinit;
bindkey "^Xa" _expand_alias
zstyle ':completion:*' completer _expand_alias _complete _ignored
zstyle ':completion:*' regular true