I think some forums with many users need this function.
Add an input box in the user registration interface and enter the reason for joining the community (what are you good at? What do you want to discuss in the community? How will you treat the community?).
After registration, you need to verify your email address and wait for the administrator's review before you can become a full member before you are allowed to post.
Users who have not passed the audit can log in, but many of them do not have permissions, just like the visitors.
Whenever a new user's registration needs to be reviewed, the person who has the authority to review the user will receive a review notice on the Flag page and wait for approval.
The working principle of this extension is like flarum/approval, but approval post is changed to approval user.
Now LowEndTalk and LowEndSpirits using VanillaForums have used the user approval function.
I think Flarum should also have such an extension to achieve this function.