The alarm sounds on the specified date and day.
When you use WiFi, it is backed up to Google Drive every 24 hours, so data is automatically maintained when you reinstall. (Android 6.0 or later)
5d7138d1d45bf64282dc3e514a2ef25f
F4:8C:2F:68:0F:AA:35:71:D1:61:7B:B3:B3:9