"Follow a SharePoint" site function

Following. Site does not change your permissions on the site. When you follow a site, it is added to your list of followed sites, so you can get back to the site more easily. It also prioritizes the news posts from that site in your news feed. And, in Viva Connections mobile (and soon, desktop), you will get a notification in your activity feed when new News is posted to the site. The only way you can become a member of a site is if you are explicitly added by a member or owner (depending on how access permissions are set up). You cannot add yourself by following, although it might seem like that if you are talking about the SharePoint site associated with a public group/Team, where you are already a Member since the group is public.