I was working with the Microsoft graph APIs and was wondering if there was an API for setting Out of Office messages for a user?
The documentation doesn't seem to have this feature.
There's automaticRepliesSetting property in user mailbox settings. That should be the one you are looking for.
The properties you can use are similar to what you have in Set-MailboxAutoReplyConfiguration so:
externalAudience
externalReplyMessage
internalReplyMessage
scheduledEndDateTime
scheduledStartDateTime
status