Maybe the land value taxes are (intentionally) too low for the super rich who own lots of land?

Maybe we need a differential land tax system that's very low taxes for small areas intended for personal living(shelter), and taxes that go up progressively the more land you own, especially if you use it to rent-seek. It should discourage land hoarding and feudalistic rent seeking.

How would farms fit in this model?

Farm land is already differently taxed in most parts of the world.

Right but we are talking about introducing a new model

What is the definition of too much land? If I save up for my entire life making $100k a year across the family and buy 100acres should the gov be able to tax me off that land?

Where has this been solved and a land value tax implemented?