Volta below chords

By adding the Volta_engraver to the relevant staff, volte can be put below chords.

\version "2.24"

\score {
  <<
    \chords { c1 c1 }
    \new Staff \with { \consists "Volta_engraver" }
    {
      \repeat volta 2 { c'1 \alternative { c' } }
    }
  >>
  \layout {
    \context {
      \Score
      \remove "Volta_engraver"
    }
  }
}