Is it possible to get timezone of a user or its calendar through Office 365 or Graph API?
I know that you can get start and end timezone from specific event. But that does not help me.
The Microsoft Graph REST API now returns a timeZone field from Get user mailbox settings.
You can also retrieve just the timezone:
GET /users/{id|userPrincipalName}/mailboxSettings/timeZone
Unfortunately the format of timezone can vary - some details are in the docs.