Hi Chris,
Based on your description, my understanding is you wonder to expand the field one by one, when you collapsed level 1 field all the fields under level 1 field will be collapsed automatically.
I test it in my own environment, I find if I collapsed the level 1 field but the fields under level 1 field werent collapsed, then I expand the level 1 field the fields under level 1 were still expanded. I suppose this issue might be caused by design behavior.
I suggest you can use the Collapse Field option to collapse these fields one by one as a workaround. You can select the last level in your pivot table and click the Collapse Field option then you will find you can collapse them one by one.
Or you can post your issue to MSDN forum for Excel to ask if there are codes can help you solve this issue.
The link of MSDN forum for Excel:
https://social.msdn.microsoft.com/Forums/en-US/home?forum=exceldev&filter=alltypes&sort=lastpostdesc
If my understanding is incorrect, please be a bit more precise explain your requirement or you can upload a screenshot so that I can get more accurate solutions to this problem. Im glad to help and follow up your reply.
Hope its helpful.
Regards,
George Zhao
TechNet Community Support