With Vertico in Doom Emacs (via the Helpful package), I find a lot of stuff like this by doing `SPC h f` and then "vertico" and a list of functions containing that string in the name pops up.
It looks like it's in Text > Database in the "Emacs Lisp" manual, not the "Emacs" manual.
It looks like it's in Text > Database in the "Emacs Lisp" manual, not the "Emacs" manual.