Office 365 administrators can update Azure AD guest accounts with photos. Guests can do the job themselves using three PowerShell commands. Other approaches work too, but this is the easiest and quickest method to do the job, especially if you have guest accounts in multiple tenants.
Organizations can choose to control updates of user photos by policy in their Office 365 tenants or allow users to go ahead and use any image they like. In this article, we explore the value of having a user photo for every Office 365 account (and Teams and Groups too) and the choices organizations must make when they decide whether to control user-driven updates.