Foxes don't attack cats?
What utter bollocks - I've seen it via CCTV, big dog fox, decided our back garden was his, stalked the bloody cat and jumped it. Huge fight between the two and the cat survived (my dad ran out and lobbed a bucket at them) but was injured, and it was a big cat as well, not a dinky little kitty, huge strapping farm cat.
And that was a truly wild country fox, we also watched him corner young badgers and attempt to take them on. We didn't feed him, no one in the area fed foxes, he'd just decided this was his patch.
If you feed foxes they will decide that area is their territory and some will defend it, by shitting everywhere, pissing up stuff and physically in some cases.
Fed foxes still have the natural desire to hunt and kill but not the need for the food so are more likely to rip into chicken coops and runs, rabbit hutches etc, and then leave the bodies.
Fed foxes tend to have less fear of dogs/humans and so are bolder, and feel much more confident to defend territory.
Feeding foxes is not to their benefit really (if you can put manage and worm treatments in their food that might help them), it stops them practicing hunting, reduces their fear of roads, people, dogs etc, stops them teaching their offspring where to hunt, stops them pushing their offspring to disperse either. In the end, it turns the beautiful wild animal into a feral parasite on human waste.. big red rats really.
OP - they won't like motion activated sprinklers much though the jet will need to be powerful enough to dissuade them from playing with it.
Allegedly they dont like human male wee... not sure if you dislike the foxes enough to send a bloke weeing round the perimeter of your garden though.
Get a bigger dog...