https://chroniclesofelyria.gamepedia.com/Geography
The initial continent is approximately 96km x 192km. For a visualization of the size, know that it is between the size of Connecticut and New Jersey. This will take a couple of IRL days to cross unimpeded.
You can watch the video and/or dev journal below, I think they answer this question pretty well :)
https://www.youtube.com/watch?v=rJR6bb9OBOc
https://chroniclesofelyria.com/forum/topic/31589/may-2019-community-journal