add markings

If you are referirng to using a MIDI keyboard to input notes, the sort of AI required to guess which hand might best play which notes isn't really there yet, not for real0time use for sure. But if you record a MIDI file then import it into MuseScor,e the AI can make some attempt at guessing. Unless the file is perfectly quanitized, though, and you're really expert at editing with MuseScore, it will almost certainly take far longer to correct the wrong guesses - and the other things that MIDI has no way of getting right, like spelling of accidentals, proper durations of notes, use of multiple voices, etc - than to simply enter the music normally.