It is recommended for vcomplete-mode to be enabled:
You can also add (vcomplete-mode) to your init file, or enable
it through the customize interface.
When vcomplete-mode is enabled, the *Completions* buffer
appears and updates automatically (by default), and the completion at
point in the *Completions* buffer is highlighted, even if
completions-highlight-face (Emacs 29+) is nil.
The following key bindings are also made available when completion is in progress:
Move point to the next displayed completion in the
*Completions* window (vcomplete-next-completion or
minibuffer-next-completion on Emacs 29+). This command may be
used to move multiple completions at a time with a prefix argument.
Move point to the next displayed completion in the
*Completions* window (vcomplete-prev-completion or
minibuffer-previous-completion on Emacs 29+). This command may
be used to move multiple completions at a time with a prefix argument.
Choose the currently highlighted completion in the
*Completions* window (vcomplete-choose-completion
or minibuffer-choose-completion on Emacs 29+).
You may use these commands without enabling vcomplete-mode
(although they won’t be bound by default). See Completion commands
for information regarding defining new commands.