Platforms rarely grant full access
On some platforms a profile can be turned into a memorial profile. It stays visible, marked to show the person has died. Other platforms will only delete the account, once you have sent in a death certificate. Neither route gives you access to private messages, backups or linked services by default.
A request like that can take weeks or even months. There are forms and checks, and sometimes a lawyer. All that time the account stays online, visible to everyone and easy to misuse.