A 200m blade length (400m diameter) is quite a leap from what I think currently are the largest wind turbines:

- https://www.ge.com/renewableenergy/wind-energy/offshore-wind... (220m diameter, 14MW)

- https://www.offshorewind.biz/2021/11/12/worlds-largest-most-... (222m diameter, 15MW)

Yes, they are still in design concept stage I believe and quite sometime from reality.

The SUMR (Segmented Ultralight Morphing Rotors) project at US Department of Energy (ARPAE) aims to design extreme-scale blades that are 200 meters long. Such blades can power 50-megawatt wind turbines and will be taller than the Eiffel Tower.