You can make text on Apple Watch easier to read by displaying it as boldface type.
Have Apple Watch use bold text. On Apple Watch, open the Settings app , go to Brightness & Text Size, then turn on Bold Text. You’ll need to restart Apple Watch for the change to take effect. You can also use iPhone to turn on Bold Text for Apple Watch—open the Apple Watch app on iPhone, tap My Watch, go to General > Accessibility, then turn on Bold Text.