I use this to test the first layer when I change filaments or make other adjustments. The square is 0.6mm high. This gives you three layers when using a 0.2mm layer height.

The square is 56mm X 56mm.

Watch the first layer for signs of overlapping or crowding of the lines. See the photo "nozzle too close to bed" for an example of the lines crowding. You may see this in the 2nd layer as well.

If your nozzle is too high you will see gaps between the lines. You don't want gaps between the lines. You want the lines to close. But just touch enough to close.

Slice this with a 0.2 layer height. I've only tested this with a 0.4 nozzle.