"Octave" clef: G-clef for tenor voices

Yes, absolutely, Dorico supports clefs that show a number above or below them to indicate that the instrument is written one or more octaves higher or lower than it sounds.

Isn’t it a peculiar convention? Tenor voices use the octave clef, but neither double basses nor piccolo flutes ever do, and guitars sometimes do, and sometimes don’t.

In any case, you can create these clefs at will in Dorico, and you’ll get an octave clef by default when you add a tenor voice instrument to a player.