Yes. As of Aug 7, 2020, all four tiers of Azure AD, Free, Office 365 Apps, Premium P1, and Premium P2 include the core SSO and federated authentication functionality.

Azure AD Premium P1 is the second-highest tier Microsoft offers with many enhanced security and management features like MFA with Conditional Access.

The only additional features Azure AD Premium P2 adds over P2 at this time are advanced Identity Protection and Identity Governance.

For more information and a feature comparison table, please see Microsoft's Azure Active Directory pricing page.