High temperature
Watch displays constant high temperature
Apple Watch Series 6
Question marked as
See the 'If your Apple Watch gets too hot' section in:
Keep Apple Watch within acceptable operating temperatures - Apple Support
If that doesn't help, your best option may be to make an appointment at the Genius Bar in an Apple Store near you and let them look at it. If that is not possible, use the online Apple Support option. Either way:
Genius Bar Reservation and Apple Support Options - Apple