You can't say 'Do you enjoy the party?' It is grammatically incorrect. 'Do you enjoy the party?' is present simple. This is used to talk about things which are always or generally true. This party is not always true - it only exists at the moment. You can say 'Do you enjoy parties?' - in general. But you can't use present simple to ask about the current party.

Its best to use present continuous, that would be "are you enjoying the party".

It sounds much nicer to use the present continuous