InSight landed in a small hollow having remarkably few rocks. This mosaic is a map of the workspace as of sol 16 (13 December 2018), before any instruments had been deployed. Gridlines are separated by 50 centimeters. Note the fluting of the ground caused by the landing rockets blowing away fine material. A 3D model is available on SketchFab.
Here is a digital elevation model of the same space. The scale is in meters.
NASA / JPL-Caltech / Doug Ellison
Digital elevation model of the InSight workspace
There is only about 15 centimeters of elevation variation across InSight's entire workspace.