As per the Provisioning Team, to be provisioned for Smart Content, one must own entitlement for AEM MS Assets Enterprise, which includes Smart Content Services or the Smart Content Services add-on SKU to AEM MS Assets.
Also, as mentioned in the Smart Content Service Onboarding Documentation [1], the Smart Content Service is available for purchase as an add-on to Experience Manager.
[1] https://experienceleague.adobe.com/docs/experience-manager-65/assets/using/enhanced-smart-tags.html?...