UE 4.26 Capture2D does not support new Water displacement

No, but its probably disabled on purpose for performance reasons.

The waves require computations each time you render them. The capture requires you to render out a specific scene.

It would essentially not work for you even if it wasn’t impossible since youd need 2 4090 to get even 20fps at 4k res…

If you absolutely need it, then you should be using something without computation. Like an alembic cache animation that loops.