I tried to start a larger world today, and started off with large world extents (10,000 km ^2) to map out continents. I found these problems:
You can’t manually scroll-wheel zoom out in Layout view anywhere near this size, but “Zoom to extents” works. If you try to zoom from here you pop into that limitation again.
3D view doesn’t cope with this well at all, 2D view is fine.
Perlin is capped at ~122km and Adv Perlin at 256km, so it was hard/ a bit too small to use to make my continents. Ideally they might visually have a higher and upper cap, but you should be allowed to type in anything.