When configuring the Add Fields (multiple) tool, it's not possible to rearrange the order of new fields without removing the previous entries.
Example:

- I already filled out the tool with three fields - field1, field2, field3 - in my desired order.
- I add a new field - newfield - but now I want it to be ordered before field1.
- I would have to delete field1, field2, and field3. Then I would have to re-add them.
A less tedious process would enable me to drag and drop the new fields within the tool to fit my desired arrangement. This would be a quality of life improvement when building models or repeating processes from the geoprocessing history.