No - The DPI scale curve only functions against the viewport size. Might add something specific for splitscreen in the future, but for now the engine leaves it up to you, since games that employ split-screen generally need to do stuff a bit differently for local multiplayer, and can’t necessarily continue to scale everything down uniformly (or shouldn’t), you generally start running up against a barrier of usable/readable from the couch.
If you can just scale yours down, I’d suggest wrapping your UI in a scale box set to user scale mode, and adjust it to whatever you need based split screen information.