The Customer Approval extension allows store owners to take the whole control of any new account creation at the storefront. Approve only real customers account and reject all spam account. Notify admin by email after each new account registration. Notify customer by email on account approval and rejection. Display a customized disapproved and pending accounts messages right at the storefront.
Please check more details here: https://www.ulmod.com/customer-approval-for-magento-2.html