ScalingMatrix

ScalingMatrix[{sx, sy, ...}] gives the matrix corresponding to scaling by a factor si along each coordinate axis.

ScalingMatrix[s, v] gives the matrix corresponding to scaling by a factor s along the direction of the vector v.

Examples

2D scaling matrix:

ScalingMatrix[{2, 3}]
(* {{2, 0}, {0, 3}} *)

Uniform scaling:

ScalingMatrix[{2, 2, 2}]
(* {{2, 0, 0}, {0, 2, 0}, {0, 0, 2}} *)

Please visit the official Wolfram Language Reference for more details.