Hi Bryan,
Your CEO is probably talking about the Managed Folders feature, which was replaced by Retention Tags and Policies in Exchange 2010.
The only approach I see for you is leveraging EWS for automating adding a folder and applying a Tag via powershell.
I found this for you:
https://blogs.perficient.com/2016/03/23/office-365-script-to-recreate-managed-folders-functionality/
I hope this helps you a bit further and calm your CEO... :)
KR, Alex
why do you differ 30,60,90 days? If you use Archiv all email from inbox stored in inbox. If you search a e-mail you can't remember is it in 30, 60 or 90-day folder.