Not quite, no. I'll just plug a random episode from my comic as an example:
if you upload a regular comic page as-is to Tapas, it still shows up like a standard comic page as you can see in the link above. In order to achieve the vertical scroll effect you must either:
A.) Draw the comic that way from the start. Either start with a single very tall canvas and just draw each panel 1 or 2 at a time moving downwards (or you can use other strategies like @JRHoch mentioned, they seem to work on many smaller canvases of 2-3 panels stacked it sounds like and then upload them all together at the end).
or
B.) You can start out by drawing a regular comic page, but then use a method similar to the video that @Moehwa linked in the first reply to rearrange the panels yourself into a vertical format.
In either case, Tapas doesn't automatically convert it for you when you upload though. You have to either plan for it, or manually do it yourself afterwards. Or just not bother like me for the time being lol