Printing the bar number for the first measure

By default, the first bar number in a score is suppressed if it is less than or equal to 1. This can be changed by setting the barNumberVisibility context property to value all-bar-numbers-visible.

\version "2.24"

\paper {
  line-width = 50\mm
}

\relative c' {
  \set Score.barNumberVisibility = #all-bar-numbers-visible
  c1 | d | e | f \break
  g1 | e | d | c
}