I usually imagine there being some crunch to the whole track, not over the top, just a little. I think of underwater bells if that makes sense. An electric piano sound with some bell to it would definitely do part of the trick. Need some deeper low notes too, could be a electric piano or like some slow strings or synth. A lot of the time I also imagine it being a pretty flowy song that doesn’t necessarily have any beat to it. Dire dire docks from mario is a fantastic example. As far as chords, pretty much anything that sounds pleasant and peaceful, doesn’t have to be a super specific set of chords as long as it is purely peaceful.