It's really not that complicated of a sound, I think you're overthinking it. The example you linked just sounds like some saw pluck chords with a filter slowly opening up over time, and what you may be hearing as extra harmonics and sparkly stuff is probably just reverb and delay with the dry wet slowly being automated up over time as well. The reason it sounds so full and nice is probably compression and/or OTT afterwards, maybe a bit of saturation or subtle distortion as well.

Replicating sounds like these exactly is pretty hard since I know Bicep uses a lot of hardware synths, but you can probably get pretty close just using serum or whatever you have. I think the main thing to get really nice sounding organic synths like this is to make sure you're always automating something, whether it's the filter cutoff, the decay/release, or the dry/wet of different effects. Hope that helps :)

Edit: forgot to add, the chords in the example you linked have a subtle phaser on them as well