https://player.vimeo.com/video/684648002?h=85feaa99c6&badge=0&autopause=0&player_id=0&app_id=58479
Cube as a child of mtPolyscale, with variation of scaling on each polygon.
You can use a vertex map or selection tags to define where scaling is performed.
Drag the tag from the Object Manager into the Selection Map link field.
The Plane on the left has a polygon selection tag, which is displayed in the viewport. An identical Plane is on the right, as a child of a mtPolyScale, defining where scaling is being performed.
The Plane on the left has a vertex map, which is displayed in the viewport. An identical Plane is on the right, as a child of a mtPolyScale. The vertex weights are defining where scaling is happening.