You can add your missed workouts manually to the Health App on the iPhone, but, as far as I remember, it will only effect the rings 24 hours after you finished the workout.
How to manually add a workout in the Health app - Apple Support
Did you already force restart your iPhone and watch? This will trigger a new sync between the devices.
To force restart the watch, press and hold the Digital Crown and the Side button together for about 10sec, until the Apple logo comes back again.
Force restart iPhone - Apple Support