You can choose whether to express the hour on a 24-hour basis or a 12-hour basis using the following hour tags, [HOUR_1_24_Z], [HOUR_1_12_Z]. If you want to display 24 or 12 hours in the way set by the system (selected by the user), you can hide a component different from the current hour mode using [IS_24H] tag.
I guess this is a frequent question and I think the original documentation should be more detailed. It only says you can use tag or conditional line, but does not explain how to do it.
For example if you have 2 same elements one in 12h format another in 24h format, both in same place, you can use the tag as follows:
opacity of 12h element: 100-100*[IS_24H]
opacity of 24h element: 0+100*[IS_24H]
Or you can use condition line:
Here is what I did in Tizen and it works also in all of my digitals in Wear OS. The idea is to separate the digital clock into 3 layers, 12H, 24H and the minute with a colon. First grab a 24H digital complication with leading zero tag, remove seconds, replace it with your bitmaps then adjust the font size same as the height of your bitmap. Duplicate the layer and lock the original to establish the position of your digital clock. Then in the duplicate layer, remove the :[MIN_Z] so that only 12H format remains, you can adjust the dimension if you want. Then reposition 24H hour format you put in. Next is duplicated again the lock layer, unlock it then remove the 24H tag you put in so that only :[MIN_Z] remains and reposition it. Next thing is to duplicate the 12H to make the 24H hour format([HOUR_0_23_Z]). Final stage in WFS(assuming that your bitmaps are correctly setup) is to work out the 12H and 24H format layers to hide using timeline but not to minute layer. Then just hide the original locked layer (serve as just pattern/position). Regarding bitmap numbers, my 12H bitmap numbers are different from the rest. 24H and minute bitmaps are single numbers, whereas 12H bitmap numbers are 2 dimension of the 2 numbers. You should start with number 1, don’t upload a 00 number. You will also have to add a Custom text strings for 10, 11 and 12. Please check my folder regarding bitmaps on my Ballozi Metron. This will surely help those who wants to rock in digitals. Take note the black background, this bitmaps are transparent and are setup to be customizable color background. This process will make you a pixel perfect designer in this career.
You can save some time & resources. You will only need that shadowed zero but also need to create custom bitmap for 10 & 20 characters (in case youre using 24H mode). Then, only one text element can be used with this tag: ([IS_24H]>0?[HOUR_0_23_Z]:[HOUR_1_12]).