With Apple's default apps, i kind of feel like the apps themselves are strategically designed to not be the best place to look for lesser trafficked use cases.

Visual customizations get upstreamed into the system accessibility settings. Extra functions are exposed exclusively in Shortcuts for you to hack together an automation feature yourself. For a fully feature supported app Apple would probably say go pay for an app (and them through fee) on the App Store.

For example with your future alarm.. you could get another app or you could create a 'Time of Day' Shortcut automation which checks everyday to see if the date is the date you want the alarm on; if it is the day create the alarm. Delete the alarm on the next day. A (not so) fun fact about automating Alarms before iOS 17: you could only delete alarms through Siri and not Shortcuts lol...