￼WA Beta Info notes that the function is not yet available. According to the site, the beta version only contains the first lines of code that indicate the presence of the function. The beta version in question is distributed via the Google Play Beta Program .
It would be the first option to automatically provide WhatsApp backups with additional security. Without this option the protection of a backup consists of the password and possible two-stage authentication on the Google account in question, or the possible protection of the local storage device of the Android device in case of an offline backup.
It is not known when the function will come. It can take a long time for WhatsApp to add functions that are referred to in the code. The first indications for a dark mode appeared in 2018 ; that feature has been officially available since Tuesday.