They may have currently x number of iPhone models... the 11 in standard and Pro, the SE, the XR(?). But...
Then also count the previous 4 generations of iPhones that they are still supporting... PLUS their current gen iPad, Air, and Pro models... PLUS the last 4 generations of those iPads... Each one and each gen has their own unique configuarations of processors, displays, etc...
All those models they still support and they can push an OS update to update ALL those units at the same gat damn time!! They are pretty amazing.
Oh and throw in the Watch OS... and AppleTV OS too since they seem to push updates to those the same time as the iPhones and iPads too.
Samsung? They toss you away after two years of software updates (now three starting with the newer models)... and I don't even know if they are so generous with cheaper models. So I wonder if they really would be supporting as many devices as Apple has at any given time.