Prepare local repository to manage macOS upgrades locally in enterprise environment.

For Apple software updates, simply deploy a Caching Server. Caching Server is build into all Macs. Purchase one with a decent size hard drive, go to Apple menu > System Settings > General > Sharing > Content Caching. Press the I button for options. Holding down the Option key on your keyboard will change the Options... button to Advanced Options... If you are on a complex corporate network with multiple routes and public IP addresses, you may need multiple caching servers and then use Advanced Options... to link them together.

Apple has a guide available here. Follow the links at the bottom for more information, including some setup examples.

There is no configuration required on the client devices. They will eventually discover the caching server and then request all future updates from it.

Hope this is helpful.

See original post. What you are looking for is caching server. You can limit it to "Only Shared Content." That will cache OS updates, OS upgrades, and apps from the App Store.