To create a 2D Plane Strain analysis, start a new Static Structural model (don't reuse the last model).

Create rectangles and circles in the X-Y plane in DM.

In Workbench, click on the Geometry cell, and in the Properties for that, set the Analysis Type to 2D.

Open the Model in Mechanical, it will show 2D and you can select the 2D type and set it to Plane Strain.