Whether it is Apple, Samsung, or another brand, these wrist devices all only detect changes in skin temperature from an established personal baseline. This can assist in menstrual cycle detection but also general health as an additional indicator of any illnesses. They do not measure actual body temperature.
But many often have these capable devices without knowing how to use the feature (or others such as fall detection, HRV, and much more). It is really worth checking what your device can do, and taking a few minutes to just set the features up if required (often an access permission must first be granted).
Currently, only the Apple Watch Series 8 and the Apple Watch Ultra (2022) can take wrist temperature readings. No models of the Apple Watch SE can take wrist temperature readings at present.