printing watch manual

If you load this link in a computer browser then you can right click on it and save as PDF,I did it with the opera web browser for my local apple watch club.

Apple Watch User Guide - Apple Support

If you open the Watch User Guide on the iPhone in Books, you have the option to share and Import it to Acrobat. That should allow you to print it. although it may be extremely large. It will also allow you to search and print only specific pages if necessary.