Haven't on the size for my landscape. Can I expand it later or stitch 2 landscapes together?

Hey all. New to the engine. I’m working on a fairly large outdoor map that uses UE4’s landscape tools to create the terrain. Say that I realize my landscape is the wrong size later in development (either too big, or more likely too small) is there an easy way to expand the existing landscape (without warping and stretching my existing terrain (sort of like making the canvas larger in Photoshop))? Or simply create a new landscape and combine it with the old one in a natural looking way where the seams between them aren’t visible? Thanks!

Same question for me.

Maps/levels are independent BUT you need to remember your initial creation settings for the exact size - you can move up from a single landscape to multiple tiles using world composition.
This enables you to build a small starting map, and a larger one later one - done properly.

When in world composition, with multiple tiles/landscapes loaded, you can brush/soften between them and the seams merge together.

You aren’t necessarily stuck with the initial size either.
You can export the Heightfiled of whatever you crafted in editor, mess with the file size in GIMP/Photoshop, save it back as the same type of file, create a new map and try to import the heightfield file.
This is a bit tedious/annoying, but if you figure out the math behind it you can somewhat quickly scale up or down what you go with minimal quality loss (you do loose quality a bit though).