Not without customizing the ‘system’ time format of the device you’re viewing things from. By default, the time format is pulled from your PC/tablet/browser’s time format settings.
The Super Tile gives you a bit more control over the layout and positioning of the time, so that extra bit of space squeezing things to the margins might help in this case, but even it doesn’t offer a 12 hour version without the AM/PM designation.
I’m also open to a feature request to improve this. Perhaps a ‘custom’ time format where you could use the HH:mm, h:mm, and other time formatting elements to build a custom format as you see fit.
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Since neither of those directly solve your need, I just updated the International Clock custom tile to support a custom time format as well. If you want to give it a try, I can walk you through updating the style on that custom tile to make the fonts larger. 