The policy practiced by Louis XIV, Peter the Great, and Frederick the Great that best encompasses their approach is Enlightened despotism.
While each of these leaders had distinct styles and policies, they generally ruled with centralized authority and made reforms aimed at modernizing their states, often influenced by Enlightenment ideas, while maintaining significant control over the government. They sought to strengthen their kingdoms and improve administration, military, and economic systems while often disregarding traditional aristocratic power structures.
While expansionism and westernization were significant features in the policies of Peter the Great (who notably pursued westernization) and Frederick the Great, the most fitting overarching policy that applies to all three is enlightened despotism. Religious tolerance varied among these leaders, with Louis XIV specifically revoking the Edict of Nantes, which had granted rights to Protestants.