>>1957793This type of hub tightens with pedaling so will require equal force to undo. If you're a strong rider it's better to upgrade to cassette.
Anyhow, one of ways is securing the tool in big, bolted down vise, and turn the wheel - plenty of leverage, multiple grip points.
Another way is taking it to car shop and ask them to use impact wrench - the hits help loosen any seizing:
https://youtu.be/jS0f4351jXk?si=dsUa6gz5iAPirftu&t=90