I'll use a splash of whole milk to reduce the acidity and slightly alter the texture.
A good way to reduce acidity without adding anything to the coffee is to prepare it Chemex-style. The types of disposable filters it uses soak up a lot of the unpleasant oil-caused factors in coffee without affecting the flavour, especially the acidity.
The inventor of the Chemex was only a modest success as a chemist, but he was quite good at marketing. He gave away free Chemex sets to famous people. A sort of "bribe the influencer" strategy. For example, the reason the the fictional James Bond is a fan of Chemex-brewed coffee is because Ian Fleming was a fan, and Ian Fleming was a fan because he was gifted a set and enjoyed it.
But despite the commercial shenanigans it really is a great way to enjoy black coffee for those with sensitivities to certain oils.