There is not one ideal temperature for every wax melt. Different warmers operate at different temperatures, and wax and fragrance formulas respond differently to heat. A warmer only needs to become hot enough to melt the product and release fragrance effectively.
For home use, the important rule is to use the warmer exactly as its manufacturer intended rather than trying to increase its temperature. Do not modify the warmer, use a higher-wattage bulb than specified, or add an outside heat source. If a melt performs poorly in one warmer, trying a properly designed warmer with a different operating style is safer than forcing more heat.
If you see temperatures in a wax-making tutorial, remember that melting and mixing wax during manufacturing is a different task from warming a finished melt at home. Do not use a maker's pouring or fragrance-mixing temperature as a target for your household warmer.
You also do not need to chase the hottest setting to get useful fragrance. Look for normal operation with the product and portion recommended for the warmer. If the wax repeatedly fails to warm as expected, check the correct bulb, dish placement, and any liner requirements before assuming the wax needs more heat.