I'm trying to make a chord sustain for an entire bar, any ideas??

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

Thanks, I'm just gonna do the guitars myself

What happens if you enter the chord and follow it with three period characters? E.g.
C...