Programming

If its something that represents mutually exclusive states, like the license plates examples (Gov't, Embassy, Learner), an enum like 4wd mentioned is a better idea than many boolean keys. This would also be the switch/case question you posed. For a "regular case", I would include that in the enum, but if you create an enum that only contains "special cases", you can always set it to null.

On the case of booleans, I would suggest avoiding them unless it is necessary, and truly a binary (as in, two-option, not binary numbers), self-contained-in-one-key thing (obligatory anti-boolean video). If the use case is to say what a different key's object represents, you don't need it (see: enums. You'll thank yourself later if you add a third option). If the use case for using it is saying another key contains value(s), you don't need it. Many languages can handle the idea of "data is present, or not present" (either with "truthy/falsey" behavior interpreting "data-or-null", or "Maybe/Option" types), so often "data-or-null" can suffice instead of booleans.

I would suggest trying to always include all keys of a present object, even if it's value is null or not applicable. It will prevent headaches later when code might try to access that key, but it isn't present. This approach might also help you decide to reduce the quantity of keys, if they could be consolidated (as in taking booleans and converting to a state-like enum, as mentioned above), or removed (if unused and/or deprecated).