You can change how individual date/time strings are displayed so long as they’re localized within the theme/extension that you’re using.
For example, if you go to Localization > Languages > your language and search for
system::lang.moment.time_format you’ll most likely see it set to ‘hh:mm a’ (formatting is either PHP DateTime or Carbon, which you’ll need to google for). You can update that to ‘HH:mm’ to turn it into 24-hour format without ‘am/pm’.
The hard part is actually finding which string you’re trying to edit - you can usually find strings by searching for them in the language editor, but time strings aren’t necessarily searchable (since searching for ‘10:00 am’ won’t find you anything), so there’s potentially some trial and error involved until you find the right string. From your examples, I’d guess that you’re looking for
system::lang.moment.date_time_format, which are the time strings used during Order creation.