\version "2.22.2"

\bookpart {
  \paper {
    tocTitleMarkup = \markup \column {
      \fill-line { "Table of Contents" }
    }
    tocItemMarkup = \markup \fill-line {
      \fromproperty #'toc:text \fromproperty #'toc:page
    }
    tocItemMarkup = \tocItemWithDotsMarkup
  }
  \markuplist \table-of-contents
  \markup {
    \null
    \hspace #4
    \column {
      \line { \with-color "white"
              "This line is blank, helps center the column line." }
      \line { "Title One" }
    }
    \hspace #1
    \draw-line #'(0 . -8)
    \hspace #2
    \column {
      \null
      \line { "Title Two" }
    }
  }
  \tocItem \markup { "Title One" }
  \score {
    \header { piece = "Title One" }
    \new Staff
      \relative c' {
        c4 c c c
      }
  }
  \tocItem \markup { "Title Two" }
  \score {
    \header { piece = "Title Two" }
    \new Staff
      \relative c' {
        c4 c c c
      }
  }
}