What spark plug you use is up to you. But the temperature range is in the part number. Every model spark plug is available in many heat ranges
For example, a standard NGK plug for the B18A1: BCPR5ES-11
The number 5 in that part number is the heat range. The higher the number, the colder the plug.
So a BCPR6ES-11 would be one heat range colder, BCPR7ES-11 two ranges coler...etc.