@Neha Bameta Thank you for reaching out to us, As I understand you want to restrict member account creation within Entra id and only have privilege to create/invite guest account.
Review this RBAC role - https://learn.microsoft.com/en-us/entra/identity/role-based-access-control/permissions-reference#guest-inviter:~:text=365%20admin%20center-,Guest%20Inviter,-Users%20in%20this
Users in this role can manage Microsoft Entra B2B guest user invitations when the Members can invite user setting is set to No.
Also, review this section Also, review this https://learn.microsoft.com/en-us/entra/identity/role-based-access-control/delegate-by-task#:~:text=Billing%20Administrator-,Users,-Expand%20table which help to achieve your ask.
Let me know if you have any further questions, feel free to post back.