Open the CAD model in Fusion 360, select the dropdown menu 'Modify', then select 'Change Parameters'.

Replace the current measurements with the values you have calculated to customize the design for your dog.

The 'shoulder to shoulder' measurement correlates to the 'shoulder_to_shoulder' parameter.

The 'harness to nose' measurement correlates to the 'harness_to_nose' parameter. You can insert your calculated value here, or replace '120' with the measurement of your dog.