How do I make writing and letters on face of Apple Watch the correct size.

You've found a cool feature! I hadn't tried it before.

The zoom feature is turned on in Settings>Accessibility. When this is on, you can zoom in on the image by double tapping with two fingers on the screen. You can scoot the image around by dragging with two fingers. Luckily, you can un-zoom again with a two finger double tap the screen.

You can turn this feature off by first clicking the crown button to bring up the apps, and then choose Settings>Accessibility>Zoom. Then tap the switch (one finger!) to turn it off.

I'm thinking, at night when it's dark and I want to check some notification that came on my phone, that this might be handy.