My new watch doesn’t have the + option to add more faces. Help!

And if you have your watch inverted, then swipe all the way to the right 😀

Deep press your watch face until you see "Customize" under the watch face.

Start swiping.

Eventually you should see a really big +

Or you can the iPhone, the "Watch" app -> Face Gallary (along the bottom)

How to add additional versions of Apple Watch faces via Apple Watch

1. Press firmly on the watch face to enter switching mode.
2. Swipe all the way to the left and tap + New button.
3. Turn the Digital Crown to select the clock face you want to add.
4. Tap the watch face to confirm.
5. Customize the new watch face version.