Blob
Reference
Mode:
Sculpt Mode
Tool:
Toolbar ‣ Blob
Similar to Draw, but vertices are pushed outwards like an inverted pinching effect. This will lead to a more consistent spherical curvature and thickening of strokes.
Brush Settings
General
Magnify
By default at 0.5 to push out the mesh during the stoke. More info at Pinch/Magnify
Note
More info at General brush settings and on Advanced brush settings.