As you know Microsoft has been recommending to turn off basic authentication protocols for some time now.

Well, until now you had to manage this by implementing an Azure AD Conditional Access policy or by implementing an authentication policies for Exchange Online.

Well, you can now manage basic authentication access for Exchange Online directly from the Office 365 administration portal.
Behind the scene this option uses Authentication policies (see https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/disable-basic-authentication-in-exchange-online#authentication-policy-procedures-in-exchange-online)

The main purpose of this new administration option is more for customers which did not have yet setup authentication policies.

To start managing it, logon to your Office 365 administration portal (https://admin.microsoft.com/) and access the SettingsOrg Settings blade to get to the Modern Authentication option under the Service tab

There you can enable the modern authentication (which should be by default now) and manage which service(s) can continue to use basic authentication