You would have to be more specific than that. These ruling on the proroguation of Parliament last year set a precedent which essentially nullifies the Royal Preroguative and means that any theoretical excercise of Royal power can be overturned by the Judges of the Supreme Court.
If there is someone who is more knowledgable on British constitional law than me who can tell me otherwise, I believe that it is now the case that legally, any remaining theoretical powers the Queen has have been destroyed and rendered null and void by this ruling because the court can simply rule that it is illegal, even when excercised by a democratically elected Prime Minister on the Queen’s behalf.
This is what I was talking about:
https://www.theguardian.com/uk/2013/jan/14/secret-papers-royals-veto-bills
It’s a total oddity with that Supreme Court ruling, given the Supreme Court’s own powers, like any other governing entity, are delegated from the Monarch.