The new diary entry writing tool was first teased for iOS 17 back in June, but it only became available on Monday with the new iPhone update - nearly three months after iOS 17 itself came out.
When you open the Journal app, tap the + button at the bottom of the page to create a new entry. If you want to start with a blank slate, when you tap 'New Entry' an empty page will appear and from there you can start typing text.
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