Working with Multiple Objects
Unlike Edit Mode, there is no multi-object editing supported for Sculpt Mode. Since sculpting often involves editing many separate objects, it is recommended to use the shortcut Alt Q while pointing at other objects, for Switching Objects quickly.
The advantage of using multiple objects is that each can have its own origin and modifiers. Splitting the geometry among multiple objects can also improve the sculpt mode performance. Alternatively objects can also be joined so there is no need to switch objects.
In the case that Face Sets were already used, joining objects or creating new geometry in Edit Mode will automatically assign new Face Sets. This makes it immediately possible to target each new geometry, for example via auto-masking. If no Face Sets are created, use the Initialize Face Sets operator to create them.