Adding an ottava marking to a single voice

If you have more than one voice on the staff, setting octavation in one voice transposes the position of notes in all voices for the duration of the ottava bracket. If the octavation is only intended to apply to one voice, the Ottava_spanner_engraver should be moved to Voice context.

\version "2.24.0"

\layout {
  \context {
    \Staff
    \remove Ottava_spanner_engraver
  }
  \context {
    \Voice
    \consists Ottava_spanner_engraver
  }
}

{
  \clef bass
  << { <g d'>1~ q2 <c' e'> }
  \\
    {
      r2.
      \ottava -1
      <b,,, b,,>4 ~ |
      q2
      \ottava 0
      <c e>2
    }
  >>
}