Pablo Dobarro has just added plasticity support to his famed sculpt mode cloth brush.
Plasticity support for softbody deformations brings with it finer granular control over the deformation patterns and behavior of the cloth brush. It also adds stability and predictability to the cloth simulation while sculpting.
This patch also solves previous issues with other brushes such as the grab brush, where the deformation was based on static coordinates driven by the softbody strength, causing artifacts in some cases.
This patch has already landed in Blender 2.91, which you can download and start experimenting with from the link below.