The royal prerogative includes the powers to appoint and dismiss ministers, regulate the civil service, issue passports, declare war, make peace, direct the actions of the military, and negotiate and ratify treaties, alliances, and international agreements.
While Elizabeth has CHOSEN to not use these powers much, any future monarch can. Just look at the U.S. in the last 6 years to see what happens when a country relies more on historical norms rather than law.
