Buy it while you can.
Fantastic Beasts: The Crimes of Grindelwald on Blu-ray 3D was released today and as expected it's selling out fast.
You can still purchase the Region A (North America, South America and South East Asia) Blu-ray 3D version on Amazon.com. Their set includes the following:
Theatrical Blu-ray 3D disc.
Extended Cut Digital.
A standard Blu-ray disc (a.k.a. 2D disc) is not included in that set.
Important note: The United Kingdom edition of that set is not region free. You'll need a Region B player to watch that edition. This is one of the reasons why the Region A edition is selling out fast.