MIDI is easy just go to the piano roll view and extend the notes: this will work unless you have a sound with natural decay that doesn't last the entire measure.

RealTracks has holds that may work.

If holds and/or MIDI with short natural decays you can convert the MIDI to audio then using Melodyne you can extend both RealTrack and audio:

https://www.celemony.com/en/start


OK, a random thought;
Why does toilet paper need a commercial? Who's not buying it?

64 bit Win 10 Pro, the latest BiaB/RB, Roland Octa-Capture audio interface, a ton of software/hardware