Calendar not syncing between iPad and iPhone 17 Pro Max after updating to iOS 26.0.1

Since downloading is 26.0.1 on my iPad it will not sync the calendar to my new iPhone 17 pro max. I have tried all the suggestions mentioned by Apple but it’s still not syncing. Any ideas that would help ? Thank you in advance.

[Re-Titled by Moderator]

Original Title: Syncing calendars