Giving everyone global admin is definitely not recommended. You can view the roles here and see which specific permissions you want to give each user: https://video2.skills-academy.com/en-us/entra/identity/role-based-access-control/delegate-by-task#external-identitiesb2c:~:text=Application%20Administrator-,External%20Identities/B2C,Expand%20table,-Task
E.g tenant creator can Create new Microsoft Entra ID or Azure AD B2C tenants. You can use a combination of them for the different roles.
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Regards,
Abiola