Lyric Boundary lines | MuseScore

AFAIK the settings in Format > Style… > Lyrics > Lyrics Text > Offset above / Offset below are overridden by the anti-collision algorithms.

This means that you cannot force lyrics to overlay any notes, beams or staves by using Format > Style…> Lyrics > Lyric Text > Offset(s). With extreme changes to these offset values, you will eventually reach a “tipping point” where the lyrics will jump to the other edge of the staff (Above to Below, or Below to Above).

Of course you can force individual pieces of lyric text to overlay anything by a) turning off the Auto-place property of the lyric word/syllable, and then b) adjusting its vertical Offset.