Easiest way is to set it up as multiple enums. You would get a page like this
Depend visibility of Enum3 on the choice in Enum1. Then set a "OnChange" microflow for Enum2 to clear Enum3 input, and for Enum3 to clear Enum2 input. At least, i thought it was not the case that when a microflow changes something, the on change would be executed, so this is not an endless loop.
That will be multiple enums. It is not possible to hide / show enum items conditionally.
There is an widget for that: https://appstore.home.mendix.com/link/app/56183/Finaps/EnumSelector
Regards,
Ronald