Thank you for using Apple Support Communities. It's my understanding that images on your Apple Watch appear larger than the expected size. I'm happy to help. It's possible the Zoom feature has been turned on. You can adjust this feature on your iPhone or Apple Watch. On your Apple Watch, open Settings, then tap General > Accessibility. On your iPhone, open the Watch app on iPhone, then tap My Watch > General > Accessibility.
Here's some additional information about Zoom and other accessibility features on your Apple Watch:
Zoom - Apple Watch User Guide
Use accessibility features on your Apple Watch
Let us know the results.
Have a fantastic day!