98.6 is body temperature on which scale?

herb198220, I agree with your idea but would say it differently. A fever is the body's reaction (also a symptom) to an infection. The body doesn't, so much fight infection better at high temperatures, but the infectious organism will die at these temperatures.

my body temperature 🌡️ is fine

Temperature varies by gender, time of day, etc. "Normal" human body temperature has been decreasing since the 1800s, and is now around 97.5°F (36.4°C).