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.Chris Smith commented
If I am ever going to stop having to hear my co-workers talk about how GMAIL is Better than O365, then MSFT needs to get with the program!!