The hot water that comes out of the hot water tap in most houses and other places comes out at a temperature of 158 F.
That 158 F is way too hot and can scald you or a child when giving them a bath or taking a bath yourself so you have to add cold water to the hot water to make it cool enough to safely shower or bathe in.
The ideal temperature for a bath is 90 F and any temperature of the water higher than 90 F is considered too hot for bath water or shower water.
Having a mixing valve on your bathtub or shower is usually code in most places for safety and if you can it might be best to turn down your hot water temperature at your water heater to a lower temperature especially if you have kids that take a shower or bath themselves.
They might get the water too hot and then be scalded by it but some kids may know to turn the water temperature down enough for their safety and comfort.
I like my bath at 90 F which is warm enough but not too hot to cause any scalding.
I use a bath thermometer to take the bath water temperature and have done so when I had young kids that I was giving a bath too.