It's simple and very basic.

Measure your car now from the ground to the wheel lip or the center of the wheel to the wheel lip.

When you get your coilover suspension on you measure again to decide how high or low to raise that part of the car. Move the collar up or down the corresponding height (hopefully you wrote this all down).

Roll the car back and forth to settle the car. Measure again and adjust accordingly. Not really rocket science. Then go get an alignment.