If you want to allow a user to be able to write and publish their own blogs without being an admin of your site, you can assign them as Editor or Author role.

You can also use this plugin: https://www.buddyboss.com/integrations/buddypress-user-blog/ to allow your members to create their own blog space.

Related Articles

• https://www.wpbeginner.com/beginners-guide/wordpress-user-roles-and-permissions
• https://wordpress.org/support/article/roles-and-capabilities