This is rather more difficult than I imagined – also smoothing out is VERY FAST at really destroying a lot of mass.
I once had this problem until I figured out a pattern that worked. After you have sculpted a detail or made a shape you like, go to the voxel remesher (at the same resolution) and check the “preserve volume” box , this will ensure that the shape doesn’t change drastically. Then smooth the surface afterward. Trying to smooth the shape without the remesher will move the surface back to its original position thus moving it far away (depending on how far it was originally). The remesher establishes a new position. As you progress through the course you may run into my post I made about this sometime ago. Hope this helps