starting with 24-hour time display (defaulting to whatever preference is set in the OS) e.g. 19:53
‘military’ time (to my understanding) would then involve always displaying a given timezone (not necessarily the one which the user is in), commonly winter-time (ignoring DST), Zulu (referring to zero-offset; UTC)
further would be rendering dates as per ISO 8601 e.g. 2021-12-31 (again, defaulting to whatever preference is set in the OS)
Ex. 0830 for 8:30 AM