There is already an Option Set data type; there is no need for a Two Option Set data type. If you want only two options, this is already currently possible with the Option Set. If you want labels and a dropdown control, just use Option Set, regardless of if you need two options or more.
A Boolean type is extraordinarily more useful to have than an additional type of option set that only allows for two. This Boolean type should default to a toggle control. This would be used whenever you just need a true/false. Setting the default of the toggle should be as simple as typing "false" in the default property.
What are the labels in a Two Option Set even for if most people just want it for the true/false? Two Option Set is not needed. Boolean is.