Some editions show, at the beginning of the piece, the archaic clefs, at a smaller size, used in the original manuscript, followed by the modern clefs. For vocal music it is not uncommon to see the the lowest and highest notes written as a chord, or “ambitus” written at a smaller size, just before the actual start of the piece.
I think the coda tool may have been used for this. Search for “incipits” and see if that helps.
You can do this using a Coda (without showing the word ‘Coda’ of course). The ambitus could be written as a pseudo-glissando between two stemless notes (hide stem in Engrave Mode), or vertically, as a stemless chord.
EDIT: took too long, ninja’d already
Thank you for the Coda advice!