On Oct 21, 2021, at 1:02 PM, Eli Zaretskii <eliz@gnu.org> wrote:

For me in Emacs 27 customize buffers default to showing only
the first line of the docstring for each variable and I
can't find a way to change this to show full docstrings.

Is this different in Emacs 28?

No, it's the same in both Emacs 27 and 28: the full doc string is
shown.

That's not what I see via emacs -Q and doing M-x customize-group for apropos:

I have to click on "More" for each one.

Howard