Though there were rumors that the Apple Watch Series 10 would get a new heart and ECG sensor, that does not appear to have happened. According to

The Series 10 offers a design upgrade, adds one big new health feature – and sets the tone for the next 10 years of Apple Watch. But it won’t change the minds of Apple Watch skeptics.

Series 10 has the largest display of any Apple Watch to date, even bigger than the first Ultra. With up to 30 percent more screen area than Series 4, 5, and 6, and up to a whopping 75 percent more than Series 3, this is a game-changer for productivity and accessibility.