It depends on the midi spec. As of 1.1, the signaling was changed to include 3.3v.
Whats really important is the current loop at 5mA so resistors would need to change for 3.3v implementations.
With 5v, you’d use a pair of 220Ω resistors, but 3.3v uses 3Ω and 10Ω resistors.
Additionally, MIDI out does not require an optocoupler.
