Is it possible to have crossed out chord tones in figured bass notation? In my specific example I have a 7-9-11 chord, and I would like to tell the player not to play the third and the fifth by having those figures crossed out. Or is there a different method of communicating this?
I don’t think there’s a native method, no.
It’s unlikely that anyone playing 7 9 and 11 would ALSO play 5 and 3.
Of course, if you wrote 742, that would guarantee it, and the player might well play those figures an octave up from the bass in any case.