I trained my previous German Shepherd to understand a conditional question. It took a few years to teach, but I would ask “What do you want? Do you want [option]?” Could be go out, food, water, treat, play, love, walk, ride.
After enough conditioning, I could ask him “What do you want?” and he would literally tell me. I’d ask him and sometimes it was clear he was just bored, and would literally start to slow wag his tail and try out options. Like he’d go up to his treats and I’d say “No, you don’t need any more of those…” and he’d get this little tail wag and then go try a toy or something. Was really handy if he ran out of water or something. I’d ask “What do you want?” and he’d lead me to his empty water bowl.
Incidentally thru different keyword use for toys, he learned to differentiate the names his favorite toys. Like his basketballs were always one of his favorites, and he comprehended that his ball had a specific name, but still fell into the category of “toy.” So if you said “Go get a toy” he might bring his basketball, but if you said “Go get your ball” he would only grab his basketball.
He sadly died a couple years ago. He imprinted a bit on one of my current dogs (also a GSD), and I’ve been trying to expand on toy names with this guy. The names he’s got down well so far are blue ball, basketball, jack, long jack, cactus, pineapple, donut, and the ring. Maybe a couple other toys I can’t think of that he’s learned. (we spoil our dogs with too many toys…) But I can tell him “Go get the cactus!” and he’ll tear off and search until he finds the specific toy.
It’s very enriching for him and really shows off the intelligence of dogs that people take for granted (intelligence definitely varies on breed tho…).