Address Line 3 is on all Acumatica screens and all forms actually pick up the data from Address Line 3. When enabled and dragged to the proper spot the line is shown on the form in Classic UI. I enabled Address Line 3 or all Acumatica screens in 24xx created a customization package and publish it in 25R1. In Modern UI, the field has dragged over using Screen Configuration. This example for the Purchase Order.

In classic the Address Line 3 shows

Is there an easy way or a tool to have fields show in the Modern UI in the same location as in Classic. I would have to think you have to go into every form in the Modern UI to use the screen configuration to move the fields to where they belong.