We announced at Ignite that we are actively working on bringing dynamic plus aliases to Office 365.
To get around existing usage, the plan is for an opt-in setting. Our ETA is to have this available for all customers by the third quarter of 2020.
I will keep you updated in Uservoice on our progress.Nem Schlecht commented
And it works with "@live.com" accounts, but not with our O365 Tentant. Frustrating.