Personal opinions may vary, but I find that I can use Xcode most effectively when I have lots of screen space.
Using my MacBook Pro 13" is fine for some "light" development work, but when the going gets serious, I always turn to my main machine, which uses a 3-monitor setup.
You may find a similar situation with a 14" MBP.
Basic development work on the laptop is okay, but one or more external monitors may be preferable.
You can size and distribute Xcode/Simulator/Documentation/Browser windows (among the screens) as you like, to create your preferred work environment.