Depends on the historian, the subfield, and the academic culture in which the historian was trained.

Every historian with at least an undergrad in history will have at least a background in certain points of philosophy relevant to history. Rarely will metaphysics be taught in those classes, but epistemology certainly, and various schools of thought which ultimately have philosophical roots like Marxism, postmodernism, etc. Beyond that, it's not necessary and historians' knowledge of it varies.

Philosophy of religion, of politics, of science, or of language are more common possibilities, but it depends on the particular historian and the subfield. Historians can usually pick up topics like ethics, aesthetics, and logic if they are so inclined, but generally they aren't directly taught in a history curriculum at least in the Anglophone world.

Beyond that though, it also depends in what culture the historian was trained. Anything can be made philosophical, but a large number of historians of the Anglophone tradition avoid getting too philosophical. I've met some French-trained historians who are amazingly well-versed in philosophy, and stereotypically German historians are as well, but I do not know if that is true. Generally, continental philosophy is a little easier to incorporate into the work of the historian than analytic philosophy, which might be why the more philosophically-rigorous historians hail from Europe.