To grant permissions to assignees to manage users and group access for a specific enterprise app, go to that app in Microsoft Entra ID and open in the Roles and Administrators list for that app. Select the new custom role and complete the user or group assignment. The assignees can manage users and group access only for the specific app.
Note: You can add the following types of groups:
Assigned groups - Manually add users or devices into a static group.
Dynamic groups (Requires Microsoft Entra ID Premium) - Automatically add users or devices to user groups or device groups based on an expression you create.
Note:
Security groups
Security groups are used for granting access to Microsoft 365 resources, such as SharePoint. They can make administration easier because you need only administer the group rather than adding users to each resource individually.
Security groups can contain users or devices. Creating a security group for devices can be used with mobile device management services, such as Intune.
Security groups can be configured for dynamic membership in Microsoft Entra ID, allowing group members or devices to be added or removed automatically based on user attributes such as department, location, or title; or device attributes such as operating system version.
Security groups can be added to a team.
Microsoft 365 Groups can ' t be members of security groups.
Microsoft 365 Groups
Microsoft 365 Groups are used for collaboration between users, both inside and outside your company. With each Microsoft 365 Group, members get a group email and shared workspace for conversations, files, and calendar events, Stream, and a Planner.
Reference:
https://learn.microsoft.com/en-us/azure/active-directory/roles/custom-enterprise-apps
https://learn.microsoft.com/en-us/microsoft-365/admin/create-groups/compare-groups?
https://learn.microsoft.com/en-us/mem/intune/apps/apps-deploy