\version "2.21.0"

\layout {
  \context {
    \Score
      \override Flag.stencil = #flat-flag
  }
}

\relative c' {
<<
  { 
    r8. d'16 d d d d  d r8 r32 d32 d[ d d d] d32 r16. }
  \\
  { r8. g,16 g g g g  g r8 r32 g32 g[ g g g] g32 r16. }
>>
}