Unless it’s the altitude of cities which is usually metric, and then it goes back to feet for aircraft altitude (though that’s an intl civil aviation rule).
There are parts of the world (mainly Russia and other ex-Soviet states) where altitude below the Transition Level is measured in metres for civil aviation purposes, but most of the world does use feet.
(Also, fixed points on the ground have elevations, not altitudes)
Unless it’s the altitude of cities which is usually metric, and then it goes back to feet for aircraft altitude (though that’s an intl civil aviation rule).