One of the few things I miss from ZBrush is the alt smooth mode (the one activated by letting go of shift while smoothing). It keeps volumes better than the standard smooth. Standard mode tends to cause shrinking (which is ok and useful a lot of times!).
I think alt smooth is based on this method: GitHub - mikolalysenko/taubin-smooth: Taubin's mesh smoothing algorithm implemented in JavaScript . Nomad’s Relax mode is cool (and I miss in in ZBrush!) but it’s a bit different than this. Relax doesn’t move the vertices along local z.