Rotating a text object

LilyPond gives you the ability to rotate any object you want, particularly markups as showed here. Alternatively, you can use the \column function to display your text vertically without rotating the letters.

\version "2.24.0"

%% http://lsr.di.unimi.it/LSR/Item?id=284

\relative c' {
  \textLengthOn
  c4^\markup { \rotate #45.0 hello }
  c4^\markup { \rotate #90.0 hello }
  r4
  c4^\markup { \column { h e l l o } }
}