I just watched the movie 'Interstellar' for the first time. Assume we have reached the point (in real life) where we are able to launch interstellar spaceships meant to colonize other planets. To do this could we launch 3 or more ships from Earth and have them somehow link up or come together in space to form a larger ship, or would the ship need to be assembled in space because of how large it would have to be? I'm imagining the space station near the end of the movie could not be built on earth due to the size of it. The movie was very interesting and it got me thinking and I'm just curious. Thanks in advance.
Warning: minor spoilers in comments.