This option is available in iPad OS:
Settings > General > Date & Time > "Show AM/PM in Status Bar"
But not iOS (I believe that space for the Location Services indicateur take precedence).
Personally, I've always adhered to the 24-hour convention, which relegates such a-notations entirely obsolete.
Do you currently reside on a submarine? Are you a *cough* dwarve?
I mean, the daily circuit of the Sun easily tips the scale . . .
