In the early 90's there was an Elephant that went nuts in Hawaii and killed and wounded a few people the police were unable to stop the elephant with side arms and shotguns. A few 223 rifles were employed to no avail by locals and it took a few guys with 30-30 pig guns and quite a few rounds to stop the cow elephant.
I lived a few miles from the San Diego wild animal park where there were Elephant, Rino, Buffalo (Black death, water and Bison)
along with all the big cats.
While hunting a year ago one of the guys in camp had come back from Africa where BIG Bird kicked the crap out of him. The Ostrich attacked him and kicked him hard, breaking a rib, I asked what he would have done different, the answer was shoot the Ostrich as soon as it got close.
Well I have a few big game rifles and one is a 375 H&H for the wild game reserve.
My old boss lives next door to the Wild Animal Actors and he asked if I would teach him to shoot and reccoment a rifle in case the lions, tigers and bears got free. We got him a BAR stalker in 338 Win with a BOSS and a red dot.
A few years ago, the CA game warden pulled into the driveway and I noticed he had an M1A scout model rather then an AR, I asked. He said the 223 bullets do not work against large animals like a wounded Horse or bear that he has had to put down. I asked what ammo, he said 180 grain soft points.
With all that said,
Most of us even those that set aside a special rifle for suvival have a deer caliber hunting rifle, some have larger. That may not have a stock pile of ammo but the box or less for hunting you have can be pressed into fending off larger problems.
In WWI the German Snipers had a steel sled they hid behind and sniped from. It stopped the 303 Brit rounds, some officers sent home for their African hunting rifles and shot through the steel sleds that protected the snipers. At some point that 375 H&H or 400NE you have in the closet may be used to stop a large animal threat, may be used to stop a truck or car.