Can I copy a storyboard from one project to another project?

To reuse a storyboard, could I simply copy it from one project to another project (then make modification to the storyboard as required)?

Can we use multiple storyboards in one application?

Apple introduced them in iOS 9 and macOS 10.11. They do exactly what I needed. They allow you to break a storyboard up into multiple, smaller storyboards. A storyboard reference ties multiple storyboards together, creating one, large, composite storyboard.

Yes you can, just make sure they are selected as your main storyboards as per image below.

Example

As @Muhammad said you can and it is very simple!

You just have to drag the Storyboard file from one project to another and select all options (The same procedure as importing anything else!).
Next, you just need to go to your project options by clicking on the project icon in the left upper side of project navigator.
Then you just need to select this storyboard to be your storyboard and that's it.