if you know what consonance and dissonance is, stacking your chords will add depth to your chords while keeping them more consonant. adding 13ths and 69ths will make them more dissonant, as well as add more depth. in this case you need to know what you want.
That sounds like a G seventh chord with an added 4th (G7add4) with the root note removed. It's beautiful and sounds like it wants to resolve to C. You also must take into account the function of the chord inside the progression. Not all chords need extension and not all extensions work on any chord.
C, B, F, D is a pretty simple chord but sounds really interesting because of the dissonance. Once you plug those notes into a Heis or a Pulv you'll know exactly what I mean by "dissonance."
Sometimes layering can work wonders. Instead of having one synth do all of the heavy lifting in a chord progression, try using layered synths (with unique timbres) that play certain notes in a chord.
well try using some fx or experiment with different chord structures maybe try a second instead of a 7th or maybe play with the fourth chord and 5th together ect. Using reverb can be great just make sure to eq and control the amount as it can over take your sound :)
Make your chord. Start with a pulv with a single sawtooth osc turned on. Add an S. Detune and turn the left tune knob to about 12 o clock. For added depth, add another sawtooth osc about -14 cents, and then a third sawtooth at about +14 cents. If you want even more size, duplicate your chord notes in a different octave. To push it into the background, add yet another S. Detune ( The Inavon method ), to bring it more forward, remove all the S. Detunes.
Since you posted this in arranging and not sound design, I guess that you're interested in the harmonic aspect of chords, as opposed to timbre or EQ. You can try to use extended chords instead of basic triads (5th., 7th., 9th., chords, etc.) You can experiment with the voicing of your chord and "open" it by using notes lower or higher in the corresponding scale than the closest notes to each other. You can simply add more notes to your chord (anything above four or five notes for a chord is considered dense). You can also combine the triads of two different chords together for a very rich, complex sounding chord. Make sure that the result fits in the context of your particular progression and harmony though. You can even vary the velocities of the notes composing a chord to bring out some notes more than the others. I sometimes make the velocities of the notes of my chords softer the lower they are in the chord, to bring out the top line more and have a softer low end. If you're interested in expanding your knowledge of chords and harmony in general, I recommend this channel (it's quite advanced, but you can get a lot from it): (link is only visible to registered users)
Stereo-Detune and Chorus are amazing for chords. Also remember to stack your layers, one synth doing the high-end, one for mids and another for the bass and mix them all together
also, make a better sound design. having a lot of voices on your chords makes them sound less dry and more lush.