As mentioned, the sudden rise in body temperature is considered to be an early symptom of COVID-19.
The body temperature measurement feature will work when the infrared camera on the Honor Play 4 phone is placed on someone's forehead.
Honor has stated the temperature will be measured by the phone's infrared camera present on the back panel.
Honor Play 4 series will be capable of measuring body temperature, the company has teased hours before the phone's launch today.
Coming back to Honor Play 4, the company in a separate post has announced that one of the phone models (most likely Honor Play 4 Pro) will pack Kirin 990 SoC and feature 40W superfast charging.