I don’t know if they added soft targetting to Classic or if it’s only on the Dragonflight client (not on to check right now) but, for soft targetting specifically, I believe there are options that were added in Dragonflight with Console variables to allow only soft targetting friendly NPCs and such.
If they added soft targetting in Classic, I would try CVar editing for it.
I know a few of the stuff from retail made it to the Classic client but I would assume that soft targetting probably isn’t one of them and there isn’t any other way than with the soft targetting accessibility option to do this afaik.